Hydrium Grenade

A 5-inch high and 2-inch thick cylinder filled with powdered hydrium, an unstable substance that can be harvested from sea water.

As an action you can throw the cylinder at a point within 30 ft, where the impact makes it explode in a blinding flash of light which destroys it. All creatures within 15 ft of this point must succeed on a DC 16 Constitution saving throw or be Stunned until the end of your next turn, and if the creature has not taken a turn in combat yet, they are also Surprised. Creatures which are immune to being Blinded automatically succeed on their saving throw and creatures which are immune to being Deafened have advantage on the saving throw.