When used to make a successful missile attack (slid as weapon on the combat board), this alchemical weapon deals its Blunt damage to the monster. It is usable only once, whether the attack succeeds or misses.
If the thrower hits and gets a natural 15 on the attack, both the intended target and the thrower take damage–including all applicable bonuses the thrower would normally be entitled to. However, the thrower cannot be reduced below 1 HP by this item.