Enzymatic Gastrostaff

This staff was found in the regurgitated remains of a mighty tarrasque's meal and is covered in a strange, magical mucus. You have resistance to acid damage while you hold this staff. The staff can be used as a magic quarterstaff and deals an extra 1d4 acid damage to any target it hits. In addition, you can use an action to touch a Medium or smaller willing creature with the staff to cast the enlarge/reduce spell from it without requiring concentration, targeting the creature with the spell's Enlarge option. While a creature is enlarged in this way, it deals double damage to objects and structures and gains 1d6 + 4 temporary hit points at the start of each of its turns, in addition to the spell's normal effects. The effect ends early if the enlarged creature falls to 0 hit points. When the effect ends, the creature gains 1 level of exhaustion. Once this property of the staff has been used, it can't be used again until the next dawn.

Versatile: This weapon can be used with one or two hands. A damage value in parentheses appears with the property—the damage when the weapon is used with two hands to make a melee attack.

Proficiency: simple, staff, quarterstaff Source: The Griffon's Saddlebag: Book Two p. 78 (Third Party)