Wondrous Item

Uncommon

A blast ooze is a 4-inch slab of ooze from a gelatinous cube that's been subjected to volatile alchemy. You can place the ooze on a solid surface using an action; it then sticks to that surface and remains there until a creature within reach of the ooze uses an action to remove it. If the target surface is a hostile creature or an object that's being worn or carried by one, you must make a Dexterity check contested by the creature's Dexterity (Acrobatics) check. You add your proficiency bonus to this check, and you succeed automatically if the target is incapacitated. On a success, you place the ooze on the target. You can use an action to carefully ignite a fuse that sticks out from the ooze using a torch, tinderbox, or similar method. This action can be done as part of the one used to place the ooze on a solid surface. If the ooze takes fire damage from a spell or other effect, such as a fireball blast, it remains unharmed but nevertheless lights the fuse. The lit fuse burns down into the center of the ooze after 1d4 rounds. When it reaches the center, the ooze explodes and is destroyed. Each creature within 10 feet of the ooze must make a DC 13 Dexterity saving throw. A creature takes 4d6 fire damage and is pushed 5 feet away from the ooze on a failed save. On a successful save, a creature takes half as much fire damage and isn't pushed. If the ooze was placed on an object that was being neither worn nor carried, that object takes the maximum amount of damage from the explosion. If the object is a door, it's forced open as part of the explosion, provided that the door could have also been opened with a successful DC 25 Strength check or lower.
If you use an action to carefully ignite the fuse, you can choose the number of rounds it takes for the fuse to burn (up to 4), instead of rolling a d4. If the fuse is lit another way, the GM rolls the d4 in secret. A lit fuse can be extinguished by a creature within reach as normal or if it's doused with water.