Chained Abomination

Fearless. The Abomination has advantage on saving throws against being frightened.

Multiattack. The Abomination makes three melee attacks and can pull a creature next to him. The creature must succeed on a DC 14 Strength saving throw or being pulled 5 ft. of the abomination and drop prone.

Venom Dagger. Melee /Ranged Weapon Attack: +10 to hit, reach 60 ft., one target. Hit: 13 (2d6 + 6) piercing damage and the creature must succeed on a DC 15 Constitution saving throw or take 22 (4d10) poison damage and become poisoned for 1 minute

Flame Shortsword. Melee/Ranged Weapon Attack: +10 to hit, 60 ft., one target. Hit: 15 (2d8+6) slashing damage and 14 (4d6) fire damage.

 Frost Longsword. Melee/Ranged Weapon Attack: +10 to hit, 60 ft., one target. Hit: 17 (2d10+6) slashing damage and 14 (3d6) cold damage.

Scimitar of Speed. Melee/Ranged Weapon Attack: +12 to hit, 60 ft., one target. Hit: 15 (2d6+8) slashing damage and the abomination can attack again with this weapon as a bonus action

Hook. Melee/Ranged Weapon Attack: +10 to hit, 60 ft., one target. Hit: 12 (1d6+8) piercing damage and the abomination can pull the target towards it up to 20 ft using the same action

The Abomination has 6 reaction in the round as long as he has all of his 6 arms.

Parry. The abomination adds 2 to its AC against one melee or ranged attack that would hit it. To do so, the abomination must see the attacker and be wielding a melee weapon. He can stack this feature multiple times on a single attack.

The Abomination can take 3 legendary actions. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Abomination regains spent legendary actions at the start of its turn. The abomination can use a single attack using 1 legendary action.

 Hook (1 action)

Regeneration (2 actions): The abomination heals 6d10 HP 

Attack (1 action)