Magic Resistance.

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

Unusual Nature.

The living spell doesn't require air, food, drink, or sleep.

Actions

Force Fist.

Melee Spell Attack: +10 to hit, reach 5 ft., one target. Hit: 26 (4d8 + 8) force damage. If the target is a Large or smaller creature, the living spell can move it up to 5 feet and move with it, without provoking opportunity attacks.

Grasping Hand.

The living spell attempts to grab a Huge or smaller creature within 5 feet of it. The target must succeed on a DC 15 Dexterity saving throw or be grappled (escape DC 15). Until the grapple ends, the target takes 15 (2d6 + 8) bludgeoning damage at the start of each of its turns. The living spell can grapple only one creature at a time and can't use Force Fist until the grapple ends.

Living Bigby's Hand