Cryogelid (Large)

Amorphous. The Cryogelid can move through a space as narrow as 1 inch wide without squeezing.

Volatile Ending. When the Cryogelid is reduced to 0 Hit Points, its unstable icy mass detonates in an explosion of jagged frost and freezing mist. All creatures within 10 feet must make a DC 16 Dexterity saving throw, taking 14 (4d6) cold damage on a failed save or half as much on a success.

Icetrap (Recharge 3–6). The Cryogelid attempts to engulf a creature within 10 feet of it. The target must make a DC 16 Dexterity saving throw or be restrained as the Cryogelid’s freezing ooze latches onto them. The restrained creature takes 21 (6d6) cold damage at the start of each of its turns while engulfed. The restrained creature can attempt a DC 16 Strength check at the end of its turn to break free. A creature that remains restrained for three turns in a row is encased in a thick layer of ice, becoming petrified until freed by external force.

Multiattack. The Cryogelid makes two Slam attacks.

Slam. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 18 (4d6 + 3) cold damage.

Frigid Eruption (Recharge 5–6). The Cryogelid bursts outward in a sudden surge of ice and snow, sending a freezing shockwave through the battlefield. Each creature within 15 feet must make a DC 16 Constitution saving throw, taking 21 (6d6) cold damage on a failed save or half as much on a success. Creatures who fail are also knocked prone as the force of the explosion sends them sliding across the icy ground. The Cryogelid may use this ability while waiting for recharge at the cost of reducing its size to the smaller variant.