Encephalon Progeny.

The gemmule matures into an encephalon cluster if not killed within 30 (4d12 + 4) days of its creation.

Magic Resistance.

The gemmule has advantage on saving throws against spells and other magical effects.

Actions

Psychic Slam.

Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 16 (3d10) psychic damage.

Bonus Actions

Leech.

The gemmule targets one creature within 5 feet of itself and forces the target to make a DC 14 Dexterity saving throw. On a failed save, the gemmule enters the target's space and attaches to the target. While the gemmule is attached, the target takes 7 (3d4) piercing damage at the start of each of its turns, and the gemmule can't use Leech again until it detaches. It can detach itself by spending 5 feet of its movement. As an action, the target or a creature within 5 feet of the target can detach the gemmule by succeeding on a DC 15 Strength check.

Encephalon Gemmule