Provided there is suitable room to accommodate its volume, a deep troll can move at half its burrowing speed through any opening large enough for a Tiny creature.

When the deep troll takes at least 15 slashing damage at one time, a chunk of its oozing flesh falls off into an unoccupied space within 5 feet of it. This flesh isn’t under the deep troll’s control, but it views the troll as an ally. The oozing flesh acts on the deep troll’s initiative and has its own action and movement. It has an AC of 10, 10 hp, and a walking speed of 15 feet. It can make one attack with a +6 to hit, and it deals 7 (2d6) acid damage on a hit. If not destroyed, the oozing flesh lives for 1 week, voraciously consuming any non-deep troll creature it encounters. After that time, it dissolves into a puddle of water and gore.

The deep troll regains 10 hp at the start of its turn. If the troll takes fire damage, this trait doesn’t function at the start of the troll’s next turn. The deep troll dies only if it starts its turn with 0 hp and doesn’t regenerate.