Bombchu (5e Equipment)
From D&D Wiki
Wondrous Item, common
A bombchu is a mouse-like device constructed of thin, glistening metal and packed with explosive powder. One is just over 1 foot long, almost 1 foot wide, and about 3 or 4 inches tall. One weighs 10 pounds.
As an action, you can activate this device by setting it down on the ground, at which point it will race forward in the direction of your choice, in a zig-zagging but straight line at high speed. It hums with a loud and distinct sound as it travels. It travels 100 feet in this direction on the turn you activate it, and an additional 100 feet in this direction at the start of each of your turns if it has not yet exploded. While it is traveling autonomously, a bombchu has an AC of 18. It travels over up any wall, over ceilings, or through any difficult terrain without slowing down. If the bombchu enters water, it continues to travel along the bottom of the reservoir unimpeded.
A traveling bombchu will explode upon entering a creature's space, taking damage, or at the end of the third turn after you activated it. When it explodes, all creatures within 5 feet of it must make a DC 13 Dexterity saving throw. If you are proficient with bombs, add your proficiency bonus to this DC. On a failed save, a target suffers 14 (4d6) thunder damage from a forceful explosion. The damage a bombchu inflicts to objects and structures is doubled.
You can make a ranged weapon attack with a bombchu by throwing it, as if it were identical to a Hyrulean bomb.