Black Cat

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

Animal Companion. Advantage on being charmed by an enemy of its ally.

Natural Predator. Will automatically hunt creatures smaller than itself unless instructed not to.

Claws. Melee Weapon Attack: +0 to hit, reach 5 ft., one target. Hit: 1 slashing damage.

Beast of Protection. Using a bonus action, the cat can polymorph into its black panther form when it feels its ally is in danger or enters combat. It remains in panther state until combat ends, the danger is neutralized, to it reaches 0 hit points. The cat gains 1 point of exhaustion until it takes a long rest.