Amulet of Faith, mark I.

Amulets of faith have these effects:
- Piety gain is 1/3 faster.
- Gods that protect from harm are more likely to do so (your piety is 1/3rd
  higher for such checks).
- Xom piety walk is 1/3 faster.
- Xom is more likely to act.
- Removing the amulet leaches away some piety, but will never cause
  excommunication, or drop piety too close to excommunication.

Amulets auto-id if the player already has a religion, or when the player
acquires a religion while wearing the amulet.

10 files changed, 116 insertions, 23 deletions

diff --git a/crawl-ref/source/dat/descript/items.txt b/crawl-ref/source/dat/descript/items.txt
index 38c200413b..b0211fad30 100644
--- a/crawl-ref/source/dat/descript/items.txt
+++ b/crawl-ref/source/dat/descript/items.txt
@@ -52,12 +52,6 @@ amulet of resist mutation
 This amulet protects its wearer from mutations, although not
 infallibly so.
 %%%%
-amulet of resist slowing
-
-This amulet protects its wearer from some magically induced forms of
-slowness, and increases the duration of enchantments which speed his
-or her actions.
-%%%%
 amulet of the gourmand
 
 This amulet protects its wearer from sickness due to eating fresh raw
@@ -70,6 +64,13 @@ This amulet repels some of the attacks of creatures which have been
 magically summoned, and also makes the wearer more resistant to
 draining attacks.
 %%%%
+amulet of faith
+
+This is a talisman crafted to call the attention of the gods to its
+wearer. This divine attention makes it easier to please your god, but
+your god is also less likely to forgive your transgressions, and the
+amulet will drain some of your divine favour when removed.
+%%%%
 ankus
 
 What mahouts steer their elephants with. It basically resembles a
diff --git a/crawl-ref/source/invent.cc b/crawl-ref/source/invent.cc
index 26b882755c..66026f63c0 100644
--- a/crawl-ref/source/invent.cc
+++ b/crawl-ref/source/invent.cc
@@ -279,7 +279,7 @@ void InvEntry::add_class_hotkeys(const item_def &i)
     const int type = i.base_type;
     if (type == OBJ_JEWELLERY)
     {
-        add_hotkey(i.sub_type >= AMU_RAGE ? '"' : '=');
+        add_hotkey(i.sub_type >= AMU_FIRST_AMULET ? '"' : '=');
         return;
     }
 
@@ -1490,11 +1490,21 @@ static std::string _operation_verb(operation_types oper)
     }
 }
 
+bool _removing_amulet_of_faith(const item_def &item, operation_types oper)
+{
+    return (oper == OPER_REMOVE
+            && item.base_type == OBJ_JEWELLERY
+            && item.sub_type == AMU_FAITH);
+}
+
 // Returns true if user OK'd it (or no warning), false otherwise.
 bool check_warning_inscriptions( const item_def& item,
                                  operation_types oper )
 {
-    if (item.is_valid() && has_warning_inscription(item, oper) )
+    if (item.is_valid()
+        && (has_warning_inscription(item, oper)
+            || (_removing_amulet_of_faith(item, oper)
+                && you.religion != GOD_NO_GOD)))
     {
         // When it's about destroying an item, don't even ask.
         // If the player really wants to do that, they'll have
diff --git a/crawl-ref/source/item_use.cc b/crawl-ref/source/item_use.cc
index fff392ac31..ea2dd24dc7 100644
--- a/crawl-ref/source/item_use.cc
+++ b/crawl-ref/source/item_use.cc
@@ -3512,6 +3512,14 @@ void jewellery_wear_effects(item_def &item)
         }
         break;
 
+    case AMU_FAITH:
+        if (you.religion != GOD_NO_GOD)
+        {
+            mpr("You feel a surge of divine interest.", MSGCH_GOD);
+            ident = ID_KNOWN_TYPE;
+        }
+        break;
+
     case AMU_THE_GOURMAND:
         // What's this supposed to achieve? (jpeg)
         you.duration[DUR_GOURMAND] = 0;
@@ -4006,6 +4014,27 @@ bool puton_ring(int slot)
     return puton_item(item_slot);
 }
 
+void remove_amulet_of_faith(item_def &item)
+{
+    if (you.religion != GOD_NO_GOD
+        && you.religion != GOD_XOM)
+    {
+        simple_god_message(" seems less interested in you.");
+
+        const int piety_loss = div_rand_round(you.piety, 3);
+        // Piety penalty for removing the Amulet of Faith.
+        if (you.piety - piety_loss > 10)
+        {
+            mprf(MSGCH_GOD,
+                 "%s leaches power out of you as you remove it.",
+                 item.name(DESC_CAP_YOUR).c_str());
+            dprf("%s: piety leach: %d",
+                 item.name(DESC_PLAIN).c_str(), piety_loss);
+            lose_piety(piety_loss);
+        }
+    }
+}
+
 void jewellery_remove_effects(item_def &item, bool mesg)
 {
     // The ring/amulet must already be removed from you.equip at this point.
@@ -4079,6 +4108,10 @@ void jewellery_remove_effects(item_def &item, bool mesg)
         you.duration[DUR_GOURMAND] = 0;
         break;
 
+    case AMU_FAITH:
+        remove_amulet_of_faith(item);
+        break;
+
     case AMU_GUARDIAN_SPIRIT:
         if (you.species == SP_DEEP_DWARF)
             mpr("Your magic begins regenerating once more.");
@@ -4173,7 +4206,7 @@ bool remove_ring(int slot, bool announce)
     }
 
     if (!check_warning_inscriptions(you.inv[you.equip[hand_used]],
-                                         OPER_REMOVE))
+                                    OPER_REMOVE))
     {
         canned_msg(MSG_OK);
         return (false);
diff --git a/crawl-ref/source/itemname.cc b/crawl-ref/source/itemname.cc
index de7df19748..fa8bbc9332 100644
--- a/crawl-ref/source/itemname.cc
+++ b/crawl-ref/source/itemname.cc
@@ -594,6 +594,8 @@ static const char* jewellery_type_name(int jeweltype)
     case AMU_INACCURACY:        return "amulet of inaccuracy";
     case AMU_RESIST_MUTATION:   return "amulet of resist mutation";
     case AMU_GUARDIAN_SPIRIT:   return "amulet of guardian spirit";
+    case AMU_FAITH:             return "amulet of faith";
+    case AMU_STASIS:            return "amulet of stasis";
     default: return "buggy jewellery";
     }
 }
@@ -2733,6 +2735,9 @@ bool is_useless_item(const item_def &item, bool temp)
                        || (player_mutation_level(MUT_HERBIVOROUS) == 3)
                        || you.species == SP_MUMMY);
 
+        case AMU_FAITH:
+            return (you.species == SP_DEMIGOD);
+
         case RING_LIFE_PROTECTION:
             return (player_prot_life(false, temp, false) == 3);
 
diff --git a/crawl-ref/source/itemprop-enum.h b/crawl-ref/source/itemprop-enum.h
index d139422610..a079cc9368 100644
--- a/crawl-ref/source/itemprop-enum.h
+++ b/crawl-ref/source/itemprop-enum.h
@@ -187,6 +187,8 @@ enum jewellery_type
     AMU_INACCURACY,
     AMU_RESIST_MUTATION,
     AMU_GUARDIAN_SPIRIT,
+    AMU_FAITH,
+    AMU_STASIS,
 
     NUM_JEWELLERY
 };
diff --git a/crawl-ref/source/makeitem.cc b/crawl-ref/source/makeitem.cc
index 7d3182f29f..748b6973a8 100644
--- a/crawl-ref/source/makeitem.cc
+++ b/crawl-ref/source/makeitem.cc
@@ -599,7 +599,7 @@ void item_colour(item_def &item)
             break;
         }
 
-        if (item.sub_type >= AMU_RAGE)
+        if (item.sub_type >= AMU_FIRST_AMULET)
         {
             switch (switchnum)
             {
@@ -1851,7 +1851,7 @@ static special_missile_type _determine_missile_brand(const item_def& item,
     case MI_ARROW:
         rc = static_cast<special_missile_type>(
                         random_choose_weighted(30, SPMSL_FLAME, 30, SPMSL_FROST,
-                                               20, SPMSL_POISONED, 15, SPMSL_REAPING, 
+                                               20, SPMSL_POISONED, 15, SPMSL_REAPING,
                                                15, SPMSL_DISPERSAL,
                                                nw, SPMSL_NORMAL,
                                                0));
diff --git a/crawl-ref/source/religion.cc b/crawl-ref/source/religion.cc
index ae6c6c1f4b..3d5fe9d31e 100644
--- a/crawl-ref/source/religion.cc
+++ b/crawl-ref/source/religion.cc
@@ -3599,6 +3599,9 @@ static void _dock_piety(int piety_loss, int penance)
     if (piety_loss <= 0 && penance <= 0)
         return;
 
+    piety_loss = piety_scale(piety_loss);
+    penance    = piety_scale(penance);
+
     if (piety_loss)
     {
         if (last_piety_lecture != you.num_turns)
@@ -3629,15 +3632,29 @@ static void _dock_piety(int piety_loss, int penance)
     }
 }
 
-void gain_piety(int pgn)
+// Scales a piety number, applying boosters (amulet of faith).
+int piety_scale(int piety)
 {
-    if (pgn <= 0)
+    if (piety < 0)
+        return (-piety_scale(-piety));
+
+    if (wearing_amulet(AMU_FAITH))
+        return (piety + div_rand_round(piety, 3));
+
+    return (piety);
+}
+
+void gain_piety(int original_gain)
+{
+    if (original_gain <= 0)
         return;
 
     // Xom uses piety differently...
     if (you.religion == GOD_NO_GOD || you.religion == GOD_XOM)
         return;
 
+    int pgn = piety_scale(original_gain);
+
     // check to see if we owe anything first
     if (you.penance[you.religion] > 0)
     {
@@ -3697,7 +3714,8 @@ void gain_piety(int pgn)
 
 #if DEBUG_PIETY
         mprf(MSGCH_DIAGNOSTICS, "Piety increasing by %d (and %d taken from "
-                                "hysteresis)", pgn, pgn_borrowed);
+                                "hysteresis, %d original)",
+             pgn, pgn_borrowed, original_gain);
 #endif
     }
 
@@ -3923,13 +3941,17 @@ void lose_piety(int pgn)
             redraw_skill(you.your_name, player_title());
 
             if (you.religion == GOD_ZIN)
-                simple_god_message(" is no longer ready to cure all your mutations.");
+                simple_god_message(
+                    " is no longer ready to cure all your mutations.");
             else if (you.religion == GOD_SHINING_ONE)
-                simple_god_message(" is no longer ready to bless your weapon.");
+                simple_god_message(
+                    " is no longer ready to bless your weapon.");
             else if (you.religion == GOD_KIKUBAAQUDGHA)
-                simple_god_message(" is no longer ready to enhance your necromancy.");
+                simple_god_message(
+                    " is no longer ready to enhance your necromancy.");
             else if (you.religion == GOD_LUGONU)
-                simple_god_message(" is no longer ready to corrupt your weapon.");
+                simple_god_message(
+                    " is no longer ready to corrupt your weapon.");
         }
 
         for (int i = 0; i < MAX_GOD_ABILITIES; ++i)
@@ -4896,6 +4918,21 @@ bool player_can_join_god(god_type which_god)
     return (true);
 }
 
+// Identify any interesting equipment when the player signs up with a
+// new Service Pro^W^Wdeity.
+void god_welcome_identify_gear()
+{
+    // Check for amulets of faith.
+    item_def *amulet = you.slot_item(EQ_AMULET);
+    if (amulet && amulet->sub_type == AMU_FAITH)
+    {
+        // The flash happens independent of item id.
+        mpr("Your amulet flashes!", MSGCH_GOD);
+        flash_view_delay(god_colour(you.religion), 300);
+        set_ident_type(*amulet, ID_KNOWN_TYPE);
+    }
+}
+
 void god_pitch(god_type which_god)
 {
     mprf("You %s the altar of %s.",
@@ -4978,6 +5015,8 @@ void god_pitch(god_type which_god)
                      you.worshipped[which_god] ? " back" : "").c_str());
     more();
 
+    god_welcome_identify_gear();
+
     // When you start worshipping a good god, you make all non-hostile
     // unholy and evil beings hostile; when you start worshipping Zin,
     // you make all non-hostile unclean and chaotic beings hostile; and
@@ -5158,9 +5197,10 @@ harm_protection_type god_protects_from_harm(god_type god, bool actual)
 {
     const int min_piety = piety_breakpoint(0);
     bool praying = (you.duration[DUR_PRAYER]
-                    && random2(you.piety) >= min_piety);
+                    && random2(piety_scale(you.piety)) >= min_piety);
     bool reliable = (you.piety > 130);
-    bool anytime = (one_chance_in(10) || x_chance_in_y(you.piety, 1000));
+    bool anytime = (one_chance_in(10) ||
+                    x_chance_in_y(piety_scale(you.piety), 1000));
     bool penance = (you.penance[god] > 0);
 
     // If actual is true, return HPT_NONE if the given god can protect
diff --git a/crawl-ref/source/religion.h b/crawl-ref/source/religion.h
index 82f112b548..36b09e4f5c 100644
--- a/crawl-ref/source/religion.h
+++ b/crawl-ref/source/religion.h
@@ -87,6 +87,7 @@ int god_colour(god_type god);
 bool player_can_join_god(god_type which_god);
 void god_pitch(god_type which_god);
 int piety_rank(int piety = -1);
+int piety_scale(int piety_change);
 void offer_items();
 bool god_hates_your_god(god_type god,
                         god_type your_god = you.religion);
diff --git a/crawl-ref/source/shopping.cc b/crawl-ref/source/shopping.cc
index 94cd11e25e..45b4f90a1f 100644
--- a/crawl-ref/source/shopping.cc
+++ b/crawl-ref/source/shopping.cc
@@ -1793,6 +1793,7 @@ unsigned int item_value( item_def item, bool ident )
                 break;
             case AMU_THE_GOURMAND:
             case AMU_GUARDIAN_SPIRIT:
+            case AMU_FAITH:
                 valued += 35;
                 break;
             case AMU_CLARITY:
diff --git a/crawl-ref/source/xom.cc b/crawl-ref/source/xom.cc
index 4a14fac513..323cb9c13e 100644
--- a/crawl-ref/source/xom.cc
+++ b/crawl-ref/source/xom.cc
@@ -233,7 +233,7 @@ static void _xom_is_stimulated(int maxinterestingness,
     if (crawl_state.which_god_acting() == GOD_XOM)
         return;
 
-    int interestingness = random2(maxinterestingness);
+    int interestingness = random2(piety_scale(maxinterestingness));
 
     interestingness = std::min(255, interestingness);
 
@@ -292,7 +292,7 @@ void xom_tick()
     int size = abs(you.piety - HALF_MAX_PIETY);
 
     // Piety slowly drifts towards the extremes.
-    int delta = (x_chance_in_y(511, 1000) ? 1 : -1);
+    const int delta = piety_scale(x_chance_in_y(511, 1000) ? 1 : -1);
     size += delta;
     if (size > HALF_MAX_PIETY)
         size = HALF_MAX_PIETY;
@@ -333,7 +333,7 @@ void xom_tick()
     if (you.gift_timeout == 1)
         simple_god_message(" is getting BORED.");
 
-    if (one_chance_in(3))
+    if (wearing_amulet(AMU_FAITH)? coinflip() : one_chance_in(3))
     {
         const int tension = get_tension(GOD_XOM);
         const int chance = (tension ==  0 ? 1 :