Gulon

Amorphous. The gulon can move through a space as narrow as 1 foot wide without squeezing. When it moves through an area smaller than its normal space, it excretes waste in a 5-foot cube. This waste is difficult terrain and creatures crossing through it must succeed on a DC 16 Constitution saving throw or become poisoned for 1 minute.

Keen Smell. The gulon has advantage on Wisdom (Perception) checks that rely on smell.

Multiattack. The gulon makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) piercing damage. If the target is a creature, it must succeed on a DC 16 Strength saving throw or be knocked prone.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

Too Full (Recharge 5-6). The gulon belches a 15-foot-radius cloud of toxic gas around itself. Each creature in the area must make a DC 16 Constitution saving throw, taking 31 (7d8) poison damage on a failed save, or half as much damage on a successful one.