Updated Kyomu effect and Magic Reflection effect

* All skills have a chance of failing at 25%, not just Shield Reflect and Reflect Damage.
* Kaite, Magic Mirror, and Shield Spell - Defense are not nullified by Kyomu.
* Item-based and Magic Mirror reflection damage Boss monsters, Kaite does not.

src/map/battle.c

@@ -6735,7 +6735,7 @@ int64 battle_calc_return_damage(struct block_list* bl, struct block_list *src, i
 #endif
 	}
 
-	if( sc && sc->data[SC_KYOMU] ) // Nullify reflecting ability
+	if (sc && sc->data[SC_KYOMU] && (!ssc || !ssc->data[SC_SHIELDSPELL_DEF])) // Nullify reflecting ability except for Shield Spell - Def
 		rdamage = 0;
 
 	return cap_value(min(rdamage,max_damage),INT_MIN,INT_MAX);

src/map/skill.c

@@ -2576,11 +2576,14 @@ static int skill_magic_reflect(struct block_list* src, struct block_list* bl, in
 	struct status_change *sc = status_get_sc(bl);
 	struct map_session_data* sd = BL_CAST(BL_PC, bl);
 
-	if( sc && sc->data[SC_KYOMU] ) // Nullify reflecting ability
-		return  0;
+	if (!sc || !sc->data[SC_KYOMU]) { // Kyomu doesn't reflect
+		// Item-based reflection - Bypasses Boss check
+		if (sd && sd->bonus.magic_damage_return && type && rnd()%100 < sd->bonus.magic_damage_return)
+			return 1;
+	}
 
-	// item-based reflection
-	if( sd && sd->bonus.magic_damage_return && type && rnd()%100 < sd->bonus.magic_damage_return )
+	// Magic Mirror reflection - Bypasses Boss check
+	if (sc && sc->data[SC_MAGICMIRROR] && rnd()%100 < sc->data[SC_MAGICMIRROR]->val2)
 		return 1;
 
 	if( is_boss(src) )
@@ -2590,11 +2593,10 @@ static int skill_magic_reflect(struct block_list* src, struct block_list* bl, in
 	if( !sc || sc->count == 0 )
 		return 0;
 
-	if( sc->data[SC_MAGICMIRROR] && rnd()%100 < sc->data[SC_MAGICMIRROR]->val2 )
-		return 1;
-
-	if( sc->data[SC_KAITE] && (src->type == BL_PC || status_get_lv(src) <= 80) )
-	{// Kaite only works against non-players if they are low-level.
+	// Kaite reflection - Does not bypass Boss check
+	if( sc->data[SC_KAITE] && (src->type == BL_PC || status_get_lv(src) <= 80) ) {
+		// Kaite only works against non-players if they are low-level.
+		// Kyomu doesn't disable Kaite, but the "skill fail chance" part of Kyomu applies to it.
 		clif_specialeffect(bl, 438, AREA);
 		if( --sc->data[SC_KAITE]->val2 <= 0 )
 			status_change_end(bl, SC_KAITE, INVALID_TIMER);
@@ -15117,13 +15119,6 @@ bool skill_check_condition_castbegin(struct map_session_data* sd, uint16 skill_i
 				return false;
 			}
 			break;
-		case LG_REFLECTDAMAGE:
-		case CR_REFLECTSHIELD:
-			if( sc && sc->data[SC_KYOMU] && rnd()%100 < 30){
-				clif_skill_fail(sd,skill_id,USESKILL_FAIL_LEVEL,0);
-				return false;
-			}
-			break;
 		case KO_JYUMONJIKIRI:
 			if (sd->weapontype1 && (sd->weapontype2 || sd->status.shield))
 				return true;

src/map/status.c

@@ -1939,7 +1939,10 @@ bool status_check_skilluse(struct block_list *src, struct block_list *target, ui
 		if (sc->data[SC_ALL_RIDING])
 			return false; //You can't use skills while in the new mounts (The client doesn't let you, this is to make cheat-safe)
 
-		if (flag == 1 && sc->data[SC_ASH] && rnd()%2 && !(status->mode&MD_BOSS)) {
+		if (flag == 1 && !(status->mode&MD_BOSS) && ( // Applies to after cast completion only and doesn't apply to Boss monsters.
+			(sc->data[SC_ASH] && rnd()%2) || // Volcanic Ash has a 50% chance of causing skills to fail.
+			(sc->data[SC_KYOMU] && rnd()%100 < 25) // Kyomu has a 25% chance of causing skills fail.
+		)) {
 			if (src->type == BL_PC)
 				clif_skill_fail((TBL_PC*)src,skill_id,USESKILL_FAIL_LEVEL,0);
 			return false;