Restored chance of NPC_PETRIFYATTACK, see issue #1811

src/map/skill.cpp

@@ -1622,7 +1622,7 @@ int skill_additional_effect(struct block_list* src, struct block_list *bl, uint1
 		break;
 
 	case NPC_PETRIFYATTACK:
-		sc_start4(src,bl,SC_STONE,50+10*skill_lv,skill_lv,0,0,skill_get_time(skill_id,skill_lv),skill_get_time2(skill_id,skill_lv));
+		sc_start4(src,bl,SC_STONE,(20*skill_lv),skill_lv,0,0,skill_get_time(skill_id,skill_lv),skill_get_time2(skill_id,skill_lv));
 		break;
 	case NPC_CURSEATTACK:
 		sc_start(src,bl,SC_CURSE,(20*skill_lv),skill_lv,skill_get_time2(skill_id,skill_lv));