You can now request that a spell miscast effect not directly kill the player

and leave him/her with at least N hp (it can still indirectly kill the player
by causing the death of a mummy, giant spore or ball lightning).  Doesn't cover
the case of a level 3 transmigration miscast deleting the robust mutation or
giving the frail mutation before causing hp damage.

The Xom bad effects code now requests (unless Xom is being nasty) that spell
miscasts not directly kill the player, rather than avoiding miscasts
alltogether if the player has low HP (which didn't cover things like miscasts
leading to death via XP drain or stat loss, in addition to it avoiding spell
miscasts much too often).


git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@7894 c06c8d41-db1a-0410-9941-cceddc491573

7 files changed, 275 insertions, 85 deletions

diff --git a/crawl-ref/source/debug.cc b/crawl-ref/source/debug.cc
index 806be6e4ab..7ac71feebd 100644
--- a/crawl-ref/source/debug.cc
+++ b/crawl-ref/source/debug.cc
@@ -5090,6 +5090,13 @@ void debug_miscast( int target_index )
 
     while (target->alive() && repeats-- > 0)
     {
+        if (kbhit())
+        {
+            mpr("Key pressed, interrupting miscast testing.");
+            getchm();
+            break;
+        }
+
         miscast->do_miscast();
         if (level != 0)
             _miscast_screen_update();
diff --git a/crawl-ref/source/fight.cc b/crawl-ref/source/fight.cc
index 7187662e87..213110157d 100644
--- a/crawl-ref/source/fight.cc
+++ b/crawl-ref/source/fight.cc
@@ -2701,7 +2701,7 @@ void melee_attack::do_miscast()
     }
 
     MiscastEffect(miscast_target, source, (spschool_flag_type) miscast_type,
-                  miscast_level, cause, NH_NEVER, hand_str, false);
+                  miscast_level, cause, NH_NEVER, 0, hand_str, false);
 
     // Don't do miscast twice for one attack.
     miscast_level = -1;
diff --git a/crawl-ref/source/mutation.cc b/crawl-ref/source/mutation.cc
index ee902d24c2..f531d437f1 100644
--- a/crawl-ref/source/mutation.cc
+++ b/crawl-ref/source/mutation.cc
@@ -2984,27 +2984,29 @@ int how_mutated(bool all, bool levels)
     return (j);
 }
 
-bool give_bad_mutation(bool failMsg, bool force_mutation)
+bool give_bad_mutation(bool failMsg, bool force_mutation, bool non_fatal)
 {
     mutation_type mutat = NUM_MUTATIONS;
 
-    switch (random2(13))
-    {
-    case 0: mutat = MUT_CARNIVOROUS; break;
-    case 1: mutat = MUT_HERBIVOROUS; break;
-    case 2: mutat = MUT_FAST_METABOLISM; break;
-    case 3: mutat = MUT_WEAK; break;
-    case 4: mutat = MUT_DOPEY; break;
-    case 5: mutat = MUT_CLUMSY; break;
-    case 6: mutat = MUT_TELEPORT; break;
-    case 7: mutat = MUT_DEFORMED; break;
-    case 8: mutat = MUT_SCREAM; break;
-    case 9: mutat = MUT_DETERIORATION; break;
-    case 10: mutat = MUT_BLURRY_VISION; break;
-    case 11: mutat = MUT_FRAIL; break;
-    case 12: mutat = MUT_LOW_MAGIC; break;
-    }
-
+    do {
+        switch (random2(13))
+        {
+        case 0: mutat = MUT_CARNIVOROUS; break;
+        case 1: mutat = MUT_HERBIVOROUS; break;
+        case 2: mutat = MUT_FAST_METABOLISM; break;
+        case 3: mutat = MUT_WEAK; break;
+        case 4: mutat = MUT_DOPEY; break;
+        case 5: mutat = MUT_CLUMSY; break;
+        case 6: mutat = MUT_TELEPORT; break;
+        case 7: mutat = MUT_DEFORMED; break;
+        case 8: mutat = MUT_SCREAM; break;
+        case 9: mutat = MUT_DETERIORATION; break;
+        case 10: mutat = MUT_BLURRY_VISION; break;
+        case 11: mutat = MUT_FRAIL; break;
+        case 12: mutat = MUT_LOW_MAGIC; break;
+        }
+    } while (non_fatal && !accept_mutation(mutat, true, true));
+    
     const bool result = mutate(mutat, failMsg, force_mutation);
     if (result)
         learned_something_new(TUT_YOU_MUTATED);
diff --git a/crawl-ref/source/mutation.h b/crawl-ref/source/mutation.h
index fb28c16378..cd6fb9d624 100644
--- a/crawl-ref/source/mutation.h
+++ b/crawl-ref/source/mutation.h
@@ -66,7 +66,8 @@ const char *mutation_name(mutation_type which_mutat, int level = -1);
 /* ***********************************************************************
  * called from: items - spells
  * *********************************************************************** */
-bool give_bad_mutation(bool failMsg = true, bool force_mutation = false);
+bool give_bad_mutation(bool failMsg = true, bool force_mutation = false,
+                       bool non_fatal = false);
 
 // last updated 12may2000 {dlb}
 /* ***********************************************************************
diff --git a/crawl-ref/source/spl-cast.cc b/crawl-ref/source/spl-cast.cc
index 82d5096de8..83d521b401 100644
--- a/crawl-ref/source/spl-cast.cc
+++ b/crawl-ref/source/spl-cast.cc
@@ -2192,15 +2192,19 @@ void exercise_spell( spell_type spell, bool spc, bool success )
         did_god_conduct( DID_SPELL_PRACTISE, exer_norm );
 }
 
+#define MAX_RECURSE 100
+
 MiscastEffect::MiscastEffect(actor* _target, int _source, spell_type _spell,
                              int _pow, int _fail, std::string _cause,
                              nothing_happens_when_type _nothing_happens,
-                             std::string _hand_str, bool _can_plural) :
+                             int _lethality_margin, std::string _hand_str,
+                             bool _can_plural) :
     target(_target), source(_source), cause(_cause), spell(_spell),
     school(SPTYP_NONE), pow(_pow), fail(_fail), level(-1), kc(KC_NCATEGORIES),
     kt(KILL_NONE), mon_target(NULL), mon_source(NULL),
-    nothing_happens_when(_nothing_happens), hand_str(_hand_str),
-    can_plural_hand(_can_plural)
+    nothing_happens_when(_nothing_happens),
+    lethality_margin(_lethality_margin),
+    hand_str(_hand_str), can_plural_hand(_can_plural)
 {
     ASSERT(is_valid_spell(_spell));
     unsigned int schools = get_spell_disciplines(_spell);
@@ -2215,12 +2219,14 @@ MiscastEffect::MiscastEffect(actor* _target, int _source,
                              spschool_flag_type _school, int _level,
                              std::string _cause,
                              nothing_happens_when_type _nothing_happens,
-                             std::string _hand_str, bool _can_plural) :
+                             int _lethality_margin, std::string _hand_str,
+                             bool _can_plural) :
     target(_target), source(_source), cause(_cause), spell(SPELL_NO_SPELL),
     school(_school), pow(-1), fail(-1), level(_level), kc(KC_NCATEGORIES),
     kt(KILL_NONE), mon_target(NULL), mon_source(NULL),
-    nothing_happens_when(_nothing_happens), hand_str(_hand_str),
-    can_plural_hand(_can_plural)
+    nothing_happens_when(_nothing_happens),
+    lethality_margin(_lethality_margin),
+    hand_str(_hand_str), can_plural_hand(_can_plural)
 {
     ASSERT(!_cause.empty());
     ASSERT(count_bits(_school) == 1);
@@ -2235,12 +2241,14 @@ MiscastEffect::MiscastEffect(actor* _target, int _source,
                              spschool_flag_type _school, int _pow, int _fail,
                              std::string _cause,
                              nothing_happens_when_type _nothing_happens,
-                             std::string _hand_str, bool _can_plural) :
+                             int _lethality_margin, std::string _hand_str,
+                             bool _can_plural) :
     target(_target), source(_source), cause(_cause), spell(SPELL_NO_SPELL),
     school(_school), pow(_pow), fail(_fail), level(-1), kc(KC_NCATEGORIES),
     kt(KILL_NONE), mon_target(NULL), mon_source(NULL),
-    nothing_happens_when(_nothing_happens), hand_str(_hand_str),
-    can_plural_hand(_can_plural)
+    nothing_happens_when(_nothing_happens),
+    lethality_margin(_lethality_margin),
+    hand_str(_hand_str), can_plural_hand(_can_plural)
 {
     ASSERT(!_cause.empty());
     ASSERT(count_bits(_school) == 1);
@@ -2250,6 +2258,11 @@ MiscastEffect::MiscastEffect(actor* _target, int _source,
     do_miscast();
 }
 
+MiscastEffect::~MiscastEffect()
+{
+    ASSERT(recursion_depth == 0);
+}
+
 void MiscastEffect::init()
 {
     ASSERT(spell != SPELL_NO_SPELL && school == SPTYP_NONE
@@ -2260,6 +2273,10 @@ void MiscastEffect::init()
     ASSERT(target != NULL);
     ASSERT(target->alive());
 
+    ASSERT(lethality_margin == 0 || target->atype() == ACT_PLAYER);
+
+    recursion_depth = 0;
+
     source_known = target_known = false;
 
     mon_target = mon_source = NULL;
@@ -2417,10 +2434,16 @@ bool MiscastEffect::neither_end_silenced()
 
 void MiscastEffect::do_miscast()
 {
+    ASSERT(recursion_depth >= 0 && recursion_depth < MAX_RECURSE);
+
+    if (recursion_depth == 0)
+        did_msg = false;
+
+    unwind_var<int> unwind_depth(recursion_depth);
+    recursion_depth++;
+
     // Repeated calls to do_miscast() on a single object instance have
-    // killed a target which was alive when the object was created,
-    // or the target is a dead but not-yet-exploded giant spore or
-    // ball lightning.
+    // killed a target which was alive when the object was created.
     if (!target->alive())
     {
         mprf(MSGCH_DIAGNOSTICS, "Miscast target '%s' already dead",
@@ -2537,9 +2560,13 @@ void MiscastEffect::do_miscast()
 
 void MiscastEffect::do_msg(bool suppress_nothing_happnes)
 {
+    ASSERT(!did_msg);
+
     if (mon_target != NULL && !mons_near(mon_target))
         return;
 
+    did_msg = true;
+
     std::string msg;
 
     if (!all_msg.empty())
@@ -2597,12 +2624,14 @@ void MiscastEffect::do_msg(bool suppress_nothing_happnes)
     mpr(msg.c_str(), msg_ch);
 }
 
-void MiscastEffect::_ouch(int dam, beam_type flavour)
+bool MiscastEffect::_ouch(int dam, beam_type flavour)
 {
-    do_msg(true);
+    // Delay do_msg() until after avoid_lethal()
 
     if (target->atype() == ACT_MONSTER)
     {
+        do_msg(true);
+
         bolt beem;
 
         beem.flavour = flavour;
@@ -2613,6 +2642,13 @@ void MiscastEffect::_ouch(int dam, beam_type flavour)
     }
     else
     {
+        dam = check_your_resists(dam, flavour);
+
+        if (avoid_lethal(dam))
+            return (false);
+
+        do_msg(true);
+
         kill_method_type method;
 
         if (source == NON_MONSTER && spell != SPELL_NO_SPELL)
@@ -2639,21 +2675,76 @@ void MiscastEffect::_ouch(int dam, beam_type flavour)
         else
             method = KILLED_BY_SOMETHING;
 
-        dam = check_your_resists(dam, flavour);
-
         bool see_source = mon_source ? you.can_see(mon_source) : false;
         ouch(dam, kill_source, method, cause.c_str(), see_source);
     }
+    return (true);
 }
 
-void MiscastEffect::_explosion()
+bool MiscastEffect::_explosion()
 {
     ASSERT(!beam.name.empty());
     ASSERT(beam.damage.num != 0 && beam.damage.size != 0);
     ASSERT(beam.flavour != BEAM_NONE);
 
+    int max_dam = beam.damage.num * beam.damage.size;
+    max_dam = check_your_resists(max_dam, beam.flavour);
+    if (avoid_lethal(max_dam))
+        return (false);
+
     do_msg(true);
     explosion(beam, false, true);
+
+    return (true);
+}
+
+bool MiscastEffect::_lose_stat(unsigned char which_stat,
+                               unsigned char stat_loss)
+{
+    if (lethality_margin <= 0)
+        return lose_stat(which_stat, stat_loss, false, cause);
+
+    if (which_stat == STAT_RANDOM)
+    {
+        const int might = you.duration[DUR_MIGHT] ? 5 : 0;
+
+        std::vector<unsigned char> stat_types;
+        if ((you.strength - might - stat_loss) > 0)
+            stat_types.push_back(STAT_STRENGTH);
+        if ((you.intel - stat_loss) > 0)
+            stat_types.push_back(STAT_INTELLIGENCE);
+        if ((you.dex - stat_loss) > 0)
+            stat_types.push_back(STAT_DEXTERITY);
+
+        if (stat_types.size() == 0)
+        {
+            if (avoid_lethal(you.hp))
+                return (false);
+            else
+                return lose_stat(which_stat, stat_loss, false, cause);
+        }
+
+        which_stat = stat_types[random2(stat_types.size())];
+    }
+
+    int val;
+
+    switch(which_stat)
+    {
+        case STAT_STRENGTH: val = you.strength; break;
+        case STAT_INTELLIGENCE: val = you.intel; break;
+        case STAT_DEXTERITY: val = you.dex; break;
+
+        default: DEBUGSTR("Invalid stat type."); return (false);
+    }
+
+    if ((val - stat_loss) <= 0)
+    {
+        if (avoid_lethal(you.hp))
+            return (false);
+    }
+
+    return lose_stat(which_stat, stat_loss, false, cause);
 }
 
 void MiscastEffect::_potion_effect(int pot_eff, int pot_pow)
@@ -2708,6 +2799,38 @@ void MiscastEffect::send_abyss()
     target->banish(cause);
 }
 
+bool MiscastEffect::avoid_lethal(int dam)
+{
+    if (lethality_margin <= 0 || (you.hp - dam) > lethality_margin)
+        return (false);
+
+    if (recursion_depth == MAX_RECURSE)
+    {
+#if DEBUG_DIAGNOSTICS || DEBUG_MISCAST
+        mpr("Couldn't avoid lethal miscast: too much recursion.",
+            MSGCH_ERROR);
+#endif
+        return (false);
+    }
+
+    if (did_msg)
+    {
+#if DEBUG_DIAGNOSTICS || DEBUG_MISCAST
+        mpr("Couldn't avoid lethal miscast: already printed message for this "
+            "miscast.", MSGCH_ERROR);
+#endif
+        return (false);
+    }
+
+#if DEBUG_DIAGNOSTICS || DEBUG_MISCAST
+    mpr("Avoided lethal miscast.", MSGCH_DIAGNOSTICS);
+#endif
+
+    do_miscast();
+
+    return (true);
+}
+
 bool MiscastEffect::_create_monster(monster_type what, int abj_deg,
                                     bool alert)
 {
@@ -3097,8 +3220,8 @@ void MiscastEffect::_translocation(int severity)
             you_msg        = "Space bends around you!";
             mon_msg_seen   = "Space bends around @the_monster@!";
             mon_msg_unseen = "A piece of empty space twists and distorts.";
-            _ouch(4 + random2avg(7, 2));
-            target->blink(false);
+            if (_ouch(4 + random2avg(7, 2)))
+                target->blink(false);
             break;
         case 5:
             if (_create_monster(MONS_SPATIAL_VORTEX, 3))
@@ -3127,7 +3250,8 @@ void MiscastEffect::_translocation(int severity)
             mon_msg_seen   = "Space warps around @the_monster!";
             mon_msg_unseen = "A piece of empty space twists and writhes.";
 
-            _ouch(5 + random2avg(9, 2));
+            if (!_ouch(5 + random2avg(9, 2)))
+                return;
 
             if (one_chance_in(3))
                 target->teleport(true);
@@ -3173,7 +3297,9 @@ void MiscastEffect::_translocation(int severity)
             mon_msg_seen   = "Space warps crazily around @the_monster@!";
             mon_msg_unseen = "A rift temporarily opens in the fabric of space!";
 
-            _ouch(9 + random2avg(17, 2));
+            if (!_ouch(9 + random2avg(17, 2)))
+                return;
+
             you_teleport_now( true );
             potion_effect(POT_CONFUSION, 60);
             break;
@@ -3435,12 +3561,11 @@ void MiscastEffect::_divination_you(int severity)
         case 0:
             if (you.is_undead)
                 mpr("You suddenly recall your previous life!");
-            else if (lose_stat(STAT_INTELLIGENCE, 1 + random2(3),
-                               false, cause))
+            else if (_lose_stat(STAT_INTELLIGENCE, 1 + random2(3)))
             {
                 mpr("You have damaged your brain!");
             }
-            else
+            else if (!did_msg)
                 mpr("You have a terrible headache.");
             break;
         case 1:
@@ -3466,12 +3591,11 @@ void MiscastEffect::_divination_you(int severity)
         case 2:
             if (you.is_undead)
                 mpr("You suddenly recall your previous life.");
-            else if (lose_stat(STAT_INTELLIGENCE, 3 + random2(3),
-                               false, cause))
+            else if (_lose_stat(STAT_INTELLIGENCE, 3 + random2(3)))
             {
                 mpr("You have damaged your brain!");
             }
-            else
+            else if (!did_msg)
                 mpr("You have a terrible headache.");
             break;
         }
@@ -3593,7 +3717,8 @@ void MiscastEffect::_necromancy(int severity)
             }
             break;
         }
-        do_msg();
+        if (!did_msg)
+            do_msg();
         break;
 
     case 2:         // much nastier
@@ -3623,7 +3748,11 @@ void MiscastEffect::_necromancy(int severity)
             if (target->atype() == ACT_PLAYER && !player_prot_life()
                 && one_chance_in(3))
             {
-                drain_exp();
+                if (lethality_margin == 0 || you.experience > 0
+                    || !avoid_lethal(you.hp))
+                {
+                    drain_exp();
+                }
                 break;
             }               // otherwise it just flows through...
 
@@ -3632,6 +3761,7 @@ void MiscastEffect::_necromancy(int severity)
             if (target->res_torment())
             {
                 you_msg = "You feel weird for a moment.";
+                do_msg();
             }
             else
             {
@@ -3639,7 +3769,6 @@ void MiscastEffect::_necromancy(int severity)
                           "your body!";
                 _ouch(15 + random2avg(23, 2));
             }
-            do_msg();
             break;
         }
         break;
@@ -3684,6 +3813,12 @@ void MiscastEffect::_necromancy(int severity)
             break;
 
         case 4:
+            if (lethality_margin > 0 && you.experience == 0
+                && avoid_lethal(you.hp))
+            {
+                return;
+            }
+
             mpr("You are engulfed in negative energy!");
 
             if (!player_prot_life())
@@ -3693,7 +3828,7 @@ void MiscastEffect::_necromancy(int severity)
             }               // otherwise it just flows through...
 
         case 5:
-            lose_stat(STAT_RANDOM, 1 + random2avg(7, 2), false, cause);
+            _lose_stat(STAT_RANDOM, 1 + random2avg(7, 2));
             break;
 
         }
@@ -3799,31 +3934,48 @@ void MiscastEffect::_transmigration(int severity)
         switch (random2(3))
         {
         case 0:
-            if (target->atype() == ACT_PLAYER)
-            {
-                mpr("Your body is flooded with distortional energies!");
-                you.magic_contamination += random2avg(35, 3);
-            }
+            you_msg = "Your body is flooded with distortional energies!";
 
-            _ouch(3 + random2avg(18, 2));
+            if (_ouch(3 + random2avg(18, 2)) && target->atype() == ACT_PLAYER)
+                you.magic_contamination += random2avg(35, 3);
             break;
 
         case 1:
+            // HACK: Avoid lethality before deleting mutation, since
+            // afterwards a message would already have been given.
+            if (lethality_margin > 0
+                && (you.hp - lethality_margin) <= 27
+                && avoid_lethal(you.hp))
+            {
+                return;
+            }
+
             if (target->atype() == ACT_PLAYER)
             {
-                mpr("You feel very strange.");
-                delete_mutation(RANDOM_MUTATION);
+                you_msg = "You feel very strange.";
+                delete_mutation(RANDOM_MUTATION, true, false,
+                                lethality_margin > 0);
             }
             _ouch(5 + random2avg(23, 2));
             break;
 
         case 2:
+            // HACK: Avoid lethality before giving mutation, since
+            // afterwards a message would already have been given.
+            if (lethality_margin > 0
+                && (you.hp - lethality_margin) <= 27
+                && avoid_lethal(you.hp))
+            {
+                return;
+            }
+
             if (target->atype() == ACT_PLAYER)
             {
-                mpr("Your body is distorted in a weirdly horrible way!");
-                const bool failMsg = !give_bad_mutation();
+                you_msg = "Your body is distorted in a weirdly horrible way!";
+                const bool failMsg = !give_bad_mutation(true, false,
+                                                        lethality_margin > 0);
                 if (coinflip())
-                    give_bad_mutation(failMsg);
+                    give_bad_mutation(failMsg, false, lethality_margin > 0);
             }
             _ouch(5 + random2avg(23, 2));
             break;
@@ -3908,7 +4060,10 @@ void MiscastEffect::_fire(int severity)
             mon_msg_seen = "Flames sear @the_monster@.";
 
             if (target->res_fire() < 0)
-                _ouch(2 + random2avg(13, 2));
+            {
+                if (!_ouch(2 + random2avg(13, 2)))
+                    return;
+            }
             else
                 do_msg();
             target->expose_to_element(BEAM_FIRE, 3);
@@ -3925,8 +4080,8 @@ void MiscastEffect::_fire(int severity)
             mon_msg_seen   = "@The_monster@ is blasted with fire.";
             mon_msg_unseen = "A flame briefly burns in thin air.";
 
-            _ouch(5 + random2avg(29, 2), BEAM_FIRE);
-            target->expose_to_element(BEAM_FIRE, 5);
+            if (_ouch(5 + random2avg(29, 2), BEAM_FIRE))
+                target->expose_to_element(BEAM_FIRE, 5);
             break;
 
         case 1:
@@ -3953,9 +4108,8 @@ void MiscastEffect::_fire(int severity)
             mon_msg_unseen = "A large flame burns hotly for a moment in the "
                              "thin air.";
 
-            _ouch(9 + random2avg(33, 2), BEAM_FIRE);
-
-            target->expose_to_element(BEAM_FIRE, 10);
+            if (_ouch(9 + random2avg(33, 2), BEAM_FIRE))
+                target->expose_to_element(BEAM_FIRE, 10);
             break;
         case 1:
             all_msg = "There is a sudden and violent explosion of flames!";
@@ -4059,7 +4213,10 @@ void MiscastEffect::_ice(int severity)
             mon_msg_seen = "@The_monster@ is covered in a thin layer of ice.";
 
             if (target->res_cold() < 0)
-                _ouch(4 + random2avg(5, 2));
+            {
+                if (!_ouch(4 + random2avg(5, 2)))
+                    return;
+            }
             else
                 do_msg();
             target->expose_to_element(BEAM_COLD, 2);
@@ -4074,9 +4231,8 @@ void MiscastEffect::_ice(int severity)
             you_msg = "Heat is drained from your body.";
             // Monster messages needed.
 
-            _ouch(5 + random2(6) + random2(7), BEAM_COLD);
-
-            target->expose_to_element(BEAM_COLD, 4);
+            if (_ouch(5 + random2(6) + random2(7), BEAM_COLD))
+                target->expose_to_element(BEAM_COLD, 4);
             break;
 
         case 1:
@@ -4102,9 +4258,8 @@ void MiscastEffect::_ice(int severity)
             you_msg      = "You are blasted with ice!";
             mon_msg_seen = "@The_monster@ is blasted with ice!";
 
-            _ouch(9 + random2avg(23, 2), BEAM_ICE);
-
-            target->expose_to_element(BEAM_COLD, 9);
+            if (_ouch(9 + random2avg(23, 2), BEAM_ICE))
+                target->expose_to_element(BEAM_COLD, 9);
             break;
         case 1:
             you_msg        = "Freezing gasses pour from your @hands@!";
@@ -4504,7 +4659,7 @@ void MiscastEffect::_poison(int severity)
             if (player_res_poison())
                 canned_msg(MSG_NOTHING_HAPPENS);
             else
-                lose_stat(STAT_RANDOM, 1, false, cause);
+                _lose_stat(STAT_RANDOM, 1);
             break;
         }
         break;
@@ -4534,7 +4689,7 @@ void MiscastEffect::_poison(int severity)
             if (player_res_poison())
                 canned_msg(MSG_NOTHING_HAPPENS);
             else
-                lose_stat(STAT_RANDOM, 1 + random2avg(5, 2), false, cause);
+                _lose_stat(STAT_RANDOM, 1 + random2avg(5, 2));
             break;
         }
         break;
diff --git a/crawl-ref/source/spl-mis.h b/crawl-ref/source/spl-mis.h
index 781e999795..c1f3dee006 100644
--- a/crawl-ref/source/spl-mis.h
+++ b/crawl-ref/source/spl-mis.h
@@ -44,16 +44,22 @@ public:
     MiscastEffect(actor* _target, int _source, spell_type _spell, int _pow,
                   int _fail, std::string _cause = "",
                   nothing_happens_when_type _nothing_happens = NH_DEFAULT,
+                  int _lethality_margin = 0,
                   std::string _hand_str = "", bool _can_plural_hand = true);
     MiscastEffect(actor* _target, int _source, spschool_flag_type _school,
                   int _level, std::string _cause,
                   nothing_happens_when_type _nothing_happens = NH_DEFAULT,
+                  int _lethality_margin = 0,
                   std::string _hand_str = "", bool _can_plural_hand = true);
     MiscastEffect(actor* _target, int _source, spschool_flag_type _school,
                   int _pow, int _fail, std::string _cause,
                   nothing_happens_when_type _nothing_happens = NH_DEFAULT,
+                  int _lethality_margin = 0,
                   std::string _hand_str = "", bool _can_plural_hand = true);
 
+
+    ~MiscastEffect();
+
     void do_miscast();
 
 private:
@@ -78,6 +84,8 @@ private:
 
     nothing_happens_when_type nothing_happens_when;
 
+    int lethality_margin;
+
     std::string hand_str;
     bool        can_plural_hand;
 
@@ -97,6 +105,9 @@ private:
 
     msg_channel_type msg_ch;
 
+    int  recursion_depth;
+    bool did_msg;
+
 private:
     void init();
     std::string get_default_cause();
@@ -104,12 +115,15 @@ private:
     bool neither_end_silenced();
 
     void do_msg(bool suppress_nothing_happens = false);
-    void _ouch(int dam, beam_type flavour = BEAM_NONE);
-    void _explosion();
+    bool _ouch(int dam, beam_type flavour = BEAM_NONE);
+    bool _explosion();
+    bool _lose_stat(unsigned char which_stat, unsigned char stat_loss);
     void _potion_effect(int pot_eff, int pow);
     bool _create_monster(monster_type what, int abj_deg, bool alert = false);
     void send_abyss();
 
+    bool avoid_lethal(int dam);
+
     void _conjuration(int severity);
     void _enchantment(int severity);
     void _translocation(int severity);
diff --git a/crawl-ref/source/xom.cc b/crawl-ref/source/xom.cc
index 7f93085920..4902fb2217 100644
--- a/crawl-ref/source/xom.cc
+++ b/crawl-ref/source/xom.cc
@@ -1103,6 +1103,14 @@ static bool _xom_is_bad(int sever, int tension)
     const bool nasty = you.penance[GOD_XOM]
                        || (you.religion == GOD_XOM && you.gift_timeout == 0);
 
+    // If not being nasty then prevent spell miscasts from killing the
+    // player.
+    int lethality_margin;
+    if (nasty)
+        lethality_margin = 0;
+    else
+        lethality_margin = random_range(1, 4);
+
     god_acting gdact(GOD_XOM);
 
     while (!done)
@@ -1120,12 +1128,13 @@ static bool _xom_is_bad(int sever, int tension)
 
             done = true;
         }
-        else if (x_chance_in_y(4, sever) && (nasty || you.hp > 12))
+        else if (x_chance_in_y(4, sever))
         {
             god_speaks(GOD_XOM, _get_xom_speech("minor miscast effect").c_str());
 
             MiscastEffect(&you, -GOD_XOM, SPTYP_RANDOM, random2(2),
-                           "the capriciousness of Xom");
+                          "the capriciousness of Xom", NH_DEFAULT,
+                          lethality_margin);
 
             done = true;
         }
@@ -1165,12 +1174,13 @@ static bool _xom_is_bad(int sever, int tension)
 
             done = true;
         }
-        else if (x_chance_in_y(6, sever) && (nasty || you.hp > 25))
+        else if (x_chance_in_y(6, sever))
         {
             god_speaks(GOD_XOM, _get_xom_speech("medium miscast effect").c_str());
 
             MiscastEffect(&you, -GOD_XOM, SPTYP_RANDOM, random2(3),
-                           "the capriciousness of Xom");
+                          "the capriciousness of Xom", NH_DEFAULT,
+                          lethality_margin);
 
             done = true;
         }
@@ -1368,12 +1378,13 @@ static bool _xom_is_bad(int sever, int tension)
                 }
             }
         }
-        else if (x_chance_in_y(14, sever) && (nasty || you.hp > 30))
+        else if (x_chance_in_y(14, sever))
         {
             god_speaks(GOD_XOM, _get_xom_speech("major miscast effect").c_str());
 
             MiscastEffect(&you, -GOD_XOM, SPTYP_RANDOM, random2(4),
-                          "the severe capriciousness of Xom");
+                          "the severe capriciousness of Xom", NH_DEFAULT,
+                          lethality_margin);
 
             done = true;
         }