Chain Abomination

Undead. The Chain Abomination doesn't require air, also can be controlled by a Lich.

Freedom of Movement. The Chain Abomination ignores difficult terrain, and magical effects can't reduce its speed or cause it to be restrained. It can spend 5 feet of movement to escape from nonmagical restraints or being grappled.

Siege Monster. The Chain Abomination deals double damage to objects and structures, and triple damage to naval vessles.

Hateful Chains. The Chain Abominations attacks are magical

Multiattack. The Chain Abomination makes three chain attacks, each of which it can replace with one use of Fling.

Chain. Melee Weapon Attack: +17 to hit, reach 30 ft., one target. Hit: 40 (5d8 + 10) bludgeoning damage, and the target is grappled (escape DC 25). Until this grapple ends, the target is restrained. The Chain Abomination has ten chains, each of which can grapple one target.

Fling. One Large or smaller object held or creature grappled by the Chain Abomination is thrown up to 60 feet in a random direction and knocked prone. If a thrown target strikes a solid surface, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 18 Dexterity saving throw or take the same damage and be knocked prone.

Heat Metal. The Chain Abomination can heat up to three of its chains with the heat metal spell.

The Chain Abomination can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Chain Abomination regains spent legendary actions at the start of its turn.

Chain Attack or Fling. The Chain Abomination makes two Chain attack or uses its Fling.

Heat Metal (Costs 2 Actions). The kraken uses Heat Metal.