Amorpho-Buddy

Keen Hearing and Smell. The buddy has advantage on Wisdom (Perception) checks that rely on hearing or smell.

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

False Appearance. While the buddy remains motionless, it is indistinguishable from an oily pool or wet rock. The buddy can take the form of any medium beast at its owner's command gaining its appearance and speeds.

Liquid Body. The buddy cannot wear armor, carry any equipment, or serve as a mount for any creature.

Pseudopod. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: (2d4 + 2) bludgeoning damage. If the target is a creature, it must succeed on a DC 11 Strength saving throw or be grappled.

Innate Spellcasting. The buddy's innate spellcasting ability is Constitution (spell save DC 11, +3 to hit with spell attacks). The buddy can innately cast the following spells based on the movement type of the creature whose form it imitates, at the highest level its owner could cast the spell, and requiring no material components:

3/day total: Thunderclap (fly), Ray Of Frost (swim), Lightning Lure (burrow), Primal Savagery (climb)