Legendary Resistance (3/Day). If the abomination fails a saving throw, it can choose to succeed instead.
Magic Resistance. The abomination has advantage on saving throws against spells and other magical effects.
Reflective Carapace. Any time the abomination is targeted by a magic missile spell, a line spell, or a spell that requires a ranged attack roll, roll a d6. On a 1 to 5, the abomination is unaffected. On a 6, the abomination is unaffected, and the effect is reflected back at the caster as though it originated from the abomination, turning the caster into the target.
Antimagic Cone. The abominations body creates an area of antimagic, as in the antimagic field spell, in a 150-foot-cone. At the start of each of its turns, the abomination decides which way the cone faces and whether the cone is active.
Undead Fortitude. If damage reduces the abomination to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the abomination drops to 1 hit point instead.
Multiattack. The abomination makes two slam attacks:
Slam. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 33 (4d12 + 7) bludgeoning damage. If the target is a Medium or smaller creature, it is grappled (escape DC 17). Until this grapple ends, the target is restrained.