Add invocation effect to Fire and Frost Brand

Casts fireball or cone of cold at expert level

doc/fixes3-7-0.txt

@@ -1511,6 +1511,7 @@ if a tree and a boulder or statue were at the same location, applying an axe
 avoid premapping outside Sokoban map to prevent showing stone glyphs
 Grimtooth is permanently poisoned, protects from poison, and can fling poison
 cursed magic whistle can teleport you to your pet
+Fire and Frost Brand can be invoked for expert level fireball or cone of cold
 
 
 Fixes to 3.7.0-x General Problems Exposed Via git Repository

include/artifact.h

@@ -68,6 +68,8 @@ enum invoke_prop_types {
     CREATE_AMMO,
     BANISH,
     FLING_POISON,
+    FIRESTORM,
+    SNOWSTORM,
     BLINDING_RAY
 };
 

include/artilist.h

@@ -147,11 +147,11 @@ static NEARDATA struct artifact artilist[] = {
       0, 7, 3500L, NO_COLOR, MAGICBANE),
 
     A("Frost Brand", LONG_SWORD, (SPFX_RESTR | SPFX_ATTK | SPFX_DEFN), 0, 0,
-      COLD(5, 0), COLD(0, 0), NO_CARY, 0, A_NONE, NON_PM, NON_PM,
+      COLD(5, 0), COLD(0, 0), NO_CARY, SNOWSTORM, A_NONE, NON_PM, NON_PM,
       0, 9, 3000L, NO_COLOR, FROST_BRAND),
 
     A("Fire Brand", LONG_SWORD, (SPFX_RESTR | SPFX_ATTK | SPFX_DEFN), 0, 0,
-      FIRE(5, 0), FIRE(0, 0), NO_CARY, 0, A_NONE, NON_PM, NON_PM,
+      FIRE(5, 0), FIRE(0, 0), NO_CARY, FIRESTORM, A_NONE, NON_PM, NON_PM,
       0, 5, 3000L, NO_COLOR, FIRE_BRAND),
 
     A("Dragonbane", BROADSWORD,

src/artifact.c

@@ -2024,6 +2024,18 @@ arti_invoke(struct obj *obj)
                 obj->age = svm.moves;
             }
             break;
+        case SNOWSTORM:
+        case FIRESTORM:
+            {
+                int storm = oart->inv_prop == SNOWSTORM ? SPE_CONE_OF_COLD : SPE_FIREBALL;
+                int skill = spell_skilltype(storm);
+                int expertise = P_SKILL(skill);
+
+                P_SKILL(skill) = P_EXPERT;
+                (void) spelleffects(storm, FALSE, TRUE);
+                P_SKILL(skill) = expertise;
+            }
+            break;
         case BLINDING_RAY:
             if (getdir((char *) 0)) {
                 if (u.dx || u.dy) {