Un-underpopulate '4's by adding sixfirhy: elec theme, unorthodox timings.

Sixfirhies move in bursts: speed 30, but act only on 4 turns out of 12.
They also get a bonus to moving compared to other actions (move cost 60%).

Damage brand is AF_ELEC -- it's unproportionately dangerous, so the numbers
only look small.

Also, electricity heals them!  It won't bring the back from over the edge
if physical part of damage got them to 0 hp or less, in this case, they'll
explode instead.

Keeping with the long tradition of Crawl's demon names, the credit for this
one goes to timecircuits' cat.

8 files changed, 59 insertions, 19 deletions

diff --git a/crawl-ref/source/dat/descript/monsters.txt b/crawl-ref/source/dat/descript/monsters.txt
index 5940e183b0..5f40ce17a2 100644
--- a/crawl-ref/source/dat/descript/monsters.txt
+++ b/crawl-ref/source/dat/descript/monsters.txt
@@ -1347,6 +1347,10 @@ A beautiful statue of silvery hue. Its eyes glow with an otherworldly radiance.
 
 It looks brittle.
 %%%%
+sixfirhy
+
+A small vile creature that moves in bursts, stopping then darting with lightning speed. The small trident it pokes people with seems to throw sparks all around.
+%%%%
 skeletal dragon
 
 A huge undead abomination, pieced together from the broken bones of many dragons.
diff --git a/crawl-ref/source/enum.h b/crawl-ref/source/enum.h
index d14fd76c9a..ac2973bb92 100644
--- a/crawl-ref/source/enum.h
+++ b/crawl-ref/source/enum.h
@@ -1702,7 +1702,7 @@ enum monster_type                      // (int) menv[].type
     MONS_BLUE_DEVIL,
     MONS_BEAST,
     MONS_IRON_DEVIL,                   //   89
-    // 90
+    MONS_SIXFIRHY,
     //
     //
     //
diff --git a/crawl-ref/source/fight.cc b/crawl-ref/source/fight.cc
index 7a3288680e..3429f71570 100644
--- a/crawl-ref/source/fight.cc
+++ b/crawl-ref/source/fight.cc
@@ -351,9 +351,11 @@ melee_attack::melee_attack(actor *attk, actor *defn,
     final_attack_delay(0), noise_factor(0), extra_noise(0), weapon(NULL),
     damage_brand(SPWPN_NORMAL), wpn_skill(SK_UNARMED_COMBAT), hands(HANDS_ONE),
     hand_half_bonus(false), art_props(0), unrand_entry(NULL),
-    attack_verb("bug"), verb_degree(), no_damage_message(),
-    special_damage_message(), unarmed_attack(), shield(NULL),
-    defender_shield(NULL), heavy_armour_penalty(0), can_do_unarmed(false),
+    attack_verb("bug"), verb_degree(),
+    no_damage_message(), special_damage_message(), unarmed_attack(),
+    special_damage_flavour(BEAM_NONE),
+    shield(NULL), defender_shield(NULL),
+    heavy_armour_penalty(0), can_do_unarmed(false),
     water_attack(false), miscast_level(-1), miscast_type(SPTYP_NONE),
     miscast_target(NULL), final_effects()
 {
@@ -933,7 +935,7 @@ bool melee_attack::player_attack()
                              defender->name(DESC_NOCAP_THE).c_str());
         }
 
-        player_hurt_monster();
+        defender->hurt(&you, damage_done, special_damage_flavour, false);
 
         if (damage_done)
             player_exercise_combat_skills();
@@ -1922,12 +1924,6 @@ int melee_attack::player_weapon_type_modify(int damage)
     return (damage);
 }
 
-bool melee_attack::player_hurt_monster()
-{
-    return damage_done && (damage_done = defender->hurt(&you, damage_done,
-                                                        BEAM_MISSILE, false));
-}
-
 void melee_attack::player_exercise_combat_skills()
 {
     const bool helpless = defender->cannot_fight();
@@ -2077,12 +2073,12 @@ bool melee_attack::player_monattk_hit_effects(bool mondied)
     }
 
 #ifdef DEBUG_DIAGNOSTICS
-    mprf(MSGCH_DIAGNOSTICS, "Special damage to %s: %d",
+    mprf(MSGCH_DIAGNOSTICS, "Special damage to %s: %d, flavour: %d",
          defender->name(DESC_NOCAP_THE).c_str(),
-         special_damage);
+         special_damage, special_damage_flavour);
 #endif
 
-    special_damage = defender->hurt(&you, special_damage, BEAM_MISSILE, false);
+    special_damage = defender->hurt(&you, special_damage, special_damage_flavour, false);
 
     if (!defender->alive())
     {
@@ -3194,6 +3190,7 @@ bool melee_attack::apply_damage_brand()
                    "You are electrocuted!"
                 :  "There is a sudden explosion of sparks!";
             special_damage = 10 + random2(15);
+            special_damage_flavour = BEAM_ELECTRICITY;
 
             // Check for arcing in water, and add the final effect.
             const coord_def& pos = defender->pos();
@@ -3639,6 +3636,7 @@ void melee_attack::player_apply_staff_damage()
             special_damage_message =
                 make_stringf("%s is jolted!",
                              defender->name(DESC_CAP_THE).c_str());
+            special_damage_flavour = BEAM_ELECTRICITY;
         }
 
         break;
@@ -4975,6 +4973,7 @@ void melee_attack::mons_apply_attack_flavour(const mon_attack_def &attk)
                 defender->res_elec(),
                 attacker->get_experience_level() +
                 random2(attacker->get_experience_level() / 2));
+        special_damage_flavour = BEAM_ELECTRICITY;
 
         if (defender->airborne())
             special_damage = special_damage * 2 / 3;
@@ -5439,6 +5438,7 @@ void melee_attack::mons_perform_attack_rounds()
 
             special_damage = 0;
             special_damage_message.clear();
+            special_damage_flavour = BEAM_NONE;
 
             // Monsters attacking themselves don't get attack flavour.
             // The message sequences look too weird.
@@ -5461,7 +5461,7 @@ void melee_attack::mons_perform_attack_rounds()
                 break;
             }
 
-            defender->hurt(attacker, damage_done + special_damage);
+            defender->hurt(attacker, damage_done + special_damage, special_damage_flavour);
 
             if (!defender->alive())
             {
@@ -5488,6 +5488,7 @@ void melee_attack::mons_perform_attack_rounds()
 
             special_damage = 0;
             special_damage_message.clear();
+            special_damage_flavour = BEAM_NONE;
             apply_damage_brand();
 
             if (!special_damage_message.empty())
@@ -5500,7 +5501,7 @@ void melee_attack::mons_perform_attack_rounds()
             }
 
             if (special_damage > 0)
-                defender->hurt(attacker, special_damage);
+                defender->hurt(attacker, special_damage, special_damage_flavour);
 
             if (!defender->alive())
             {
diff --git a/crawl-ref/source/fight.h b/crawl-ref/source/fight.h
index 3b18c6fea1..70e29f2a02 100644
--- a/crawl-ref/source/fight.h
+++ b/crawl-ref/source/fight.h
@@ -127,6 +127,7 @@ public:
     std::string no_damage_message;
     std::string special_damage_message;
     std::string unarmed_attack;
+    beam_type special_damage_flavour;
 
     item_def  *shield;
     item_def  *defender_shield;
@@ -261,7 +262,6 @@ private:
     bool player_hits_monster();
     int  player_calc_base_weapon_damage();
     int  player_calc_base_unarmed_damage();
-    bool player_hurt_monster();
     void player_exercise_combat_skills();
     bool player_monattk_final_hit_effects(bool mondied);
     bool player_monattk_hit_effects(bool mondied);
diff --git a/crawl-ref/source/item_use.cc b/crawl-ref/source/item_use.cc
index 698a066220..515c54c414 100644
--- a/crawl-ref/source/item_use.cc
+++ b/crawl-ref/source/item_use.cc
@@ -1880,7 +1880,16 @@ static bool _charged_hit_victim(bolt &beam, actor* victim, int &dmg,
     if (victim->airborne() || victim->res_elec() > 0 || !one_chance_in(3))
         return (false);
 
-    dmg += 10 + random2(15);
+    // A hack and code duplication, but that's easier than adding accounting
+    // for each of multiple brands.
+    if (victim->id() == MONS_SIXFIRHY)
+    {
+        if (!beam.is_tracer)
+            victim->heal(10 + random2(15), false);
+        // physical damage is still done
+    }
+    else
+        dmg += 10 + random2(15);
 
     if (beam.is_tracer)
         return (false);
@@ -1888,6 +1897,8 @@ static bool _charged_hit_victim(bolt &beam, actor* victim, int &dmg,
     if (you.can_see(victim))
         if (victim->atype() == ACT_PLAYER)
             dmg_msg = "You are electrocuted!";
+        else if (victim->id() == MONS_SIXFIRHY)
+            dmg_msg = victim->name(DESC_CAP_THE) + " is charged up!";
         else
             dmg_msg = "There is a sudden explosion of sparks!";
 
diff --git a/crawl-ref/source/mon-act.cc b/crawl-ref/source/mon-act.cc
index 1501d747a8..d930815296 100644
--- a/crawl-ref/source/mon-act.cc
+++ b/crawl-ref/source/mon-act.cc
@@ -1747,7 +1747,9 @@ static void _handle_monster_move(monsters *monster)
 
         _monster_regenerate(monster);
 
-        if (monster->cannot_act())
+        if (monster->cannot_act()
+            || monster->type == MONS_SIXFIRHY // these move only 4 of 12 turns
+               && ++monster->number / 4 % 3 != 2)  // but are not helpless
         {
             monster->speed_increment -= non_move_energy;
             continue;
diff --git a/crawl-ref/source/mon-data.h b/crawl-ref/source/mon-data.h
index 9c24c20fff..ae377d7c15 100644
--- a/crawl-ref/source/mon-data.h
+++ b/crawl-ref/source/mon-data.h
@@ -3687,6 +3687,19 @@ static monsterentry mondata[] = {
 },
 
 {
+    MONS_SIXFIRHY, '4', LIGHTBLUE, "sixfirhy",
+    M_NO_FLAGS,
+    MR_NO_FLAGS, // can't have RES_ELEC since most sources of damage do nothing
+                 // in that case.  We want to "suffer" the damage to get healed.
+    0, 6, MONS_SIXFIRHY, MONS_SIXFIRHY, MH_DEMONIC, -6,
+    { {AT_HIT, AF_ELEC, 12}, AT_NO_ATK, AT_NO_ATK, AT_NO_ATK },
+    { 6, 3, 5, 0 },
+    2, 20, MST_NO_SPELLS, CE_NOCORPSE, Z_NOZOMBIE, S_SILENT,
+    I_NORMAL, HT_LAND, FL_NONE, 30, MOVE_ENERGY(6), // speed is cut to 1/3 later
+    MONUSE_OPEN_DOORS, MONEAT_NOTHING, SIZE_LITTLE
+},
+
+{
     MONS_HELLWING, '4', LIGHTGREY, "hellwing",
     M_SPELLCASTER,
     MR_RES_POISON,
diff --git a/crawl-ref/source/monster.cc b/crawl-ref/source/monster.cc
index 8d37374679..ede1fd4807 100644
--- a/crawl-ref/source/monster.cc
+++ b/crawl-ref/source/monster.cc
@@ -5881,6 +5881,15 @@ item_type_id_state_type monsters::drink_potion_effect(potion_type ptype)
 
 void monsters::react_to_damage(int damage, beam_type flavour, kill_category whose)
 {
+    if (type == MONS_SIXFIRHY && flavour == BEAM_ELECTRICITY)
+    {
+        if (!alive()) // overcharging is deadly
+            simple_monster_message(this, " explodes in an explosion of sparks!");
+        else if (heal(damage*2, false))
+            simple_monster_message(this, " seems to be charged up!");
+        return;
+    }
+
     if (!alive())
         return;