Fixed Estun not damaging all monsters (#5293)

*Estun should damage monsters of all sizes, but only stun medium sized monsters

src/map/battle.cpp

@@ -6320,8 +6320,8 @@ struct Damage battle_calc_magic_attack(struct block_list *src,struct block_list
 					case SL_STIN: //Target size must be small (0) for full damage
 						skillratio += (tstatus->size != SZ_SMALL ? -99 : 10 * skill_lv);
 						break;
-					case SL_STUN: //Full damage is dealt on small/medium targets
-						skillratio += (tstatus->size != SZ_BIG ? 5 * skill_lv : -99);
+					case SL_STUN:
+						skillratio += 5 * skill_lv;
 						break;
 					case SL_SMA: //Base damage is 40% + lv%
 						skillratio += -60 + status_get_lv(src);