Amorphous. The volatile mass can move thru a space as narrow as 1 in. wide w/o squeezing. The volatile mass can share another creature’s space. Creatures other than oozes treat the volatile mass as difficult terrain.

Elemental Potency. When the volatile mass takes cold, fire, lightning, or thunder damage, some of the elemental energy lingers in the ooze, causing its Pseudopod attacks to deal an additional 14 (4d6) damage of the same type it just took. This effect lasts for 1 min. If this trait's triggered again while already active, the extra damage remains 14 (4d6), but the damage type changes to the new type, & the duration's reset to 1 min.

Explosive Demise. When the volatile mass' reduced to 0 hp it explodes in a shower of acid. Creatures w/i 20 ft. of the volatile mass (but not those in its space) must succeed on a DC 17 Dex saving throw or take 21 (6d6) acid damage, or half as much damage on a success.

Vulnerable Interior. Attacks made against the volatile mass from w/i its space're made w/ advantage. The volatile mass loses all resistances & immunities to damage from attacks made from w/i its space.

Multiattack. The volatile mass makes 2 attacks.

Pseudopod. Melee Weapon Attack: +9 to hit, reach 10 ft., 1 target. Hit: 21 (4d6 + 7) bludgeoning damage plus 14 (4d6) acid damage.

Violent Expulsion. Melee Weapon Attack: +9 to hit, reach 0 ft., 1 target in the volatile mass’s space. Hit: 21 (4d6 + 7) bludgeoning damage plus 14 (4d6) acid damage, & the target must succeed on a DC 17 Str saving throw or be thrown up to 20 ft. away from the volatile mass, taking 7 (2d6) bludgeoning damage & falling prone.