Unstable form. The abomination's form constantly shifts and changes. Whenever it's attacked, roll 1d8 and add it to it's AC. If it has to roll a STR, CON or DEX saving throw add a 1d8 to the result.

Mutation: The abomination grows two new limbs to attack with. Roll 2d20 and attack with each limb once.

1) Bear Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) piercing damage.

2) Bear Claws. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

3) Octopus Tentacles. Melee Weapon Attack: +5 to hit, reach 15 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage. If the target is a creature, it is grappled (escape DC 16). Until this grapple ends, the target is restrained, and the abomination can't use its tentacles on another target.

4) Shark Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) piercing damage.

5) Scorpion Sting. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 7 (1d10 + 2) piercing damage, and the target must make a DC 12 Constitution saving throw, taking 22 (4d10) poison damage on a failed save, or half as much damage on a successful one.

6) Elephant Tusk. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 19 (3d8 + 6) piercing damage.

7) Ankheg Acid Spit. The abomination spits acid in a line that is 30 feet long and 5 feet wide, provided that it has no creature grappled. Each creature in that line must make a DC 13 Dexterity saving throw, taking 10 (3d6) acid damage on a failed save, or half as much damage on a successful one.

8) Hook Horror Hook. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

9) Manticore Tail Spike. Ranged Weapon Attack: +5 to hit, range 100/200 ft., one target. Hit: 7 (1d8 + 3) piercing damage.

10) Phase Spider Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 7 (1d10 + 2) piercing damage, and the target must make a DC 13 Constitution saving throw, taking 18 (4d8) poison damage on a failed save, or half as much damage on a successful one. If the poison damage reduces the target to 0 hit points, the target is stable but poisoned for 1 hour, even after regaining hit points, and is paralyzed while poisoned in this way.

11) Gorgon Hooves. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 16 (2d10 + 5) bludgeoning damage.

12) Chuul Pincer. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 11 (2d6 + 4) bludgeoning damage. The target is grappled (escape DC 14) if it is a Large or smaller creature.

13) Hulking Crab Claw. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 20 (3d10 + 4) bludgeoning damage, and the target is grappled (escape DC 15). 

14) Hippogriff Beak. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 8 (1d10 + 3) piercing damage.

15) Saber-Toothed Tiger Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (1d10 + 5) piercing damage.

16) Saber-Toothed Tiger Claw. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) slashing damage.

17) Elk Antler. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 11 (2d6 + 4) bludgeoning damage.

18) Elk Hooves. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 22 (4d8 + 4) bludgeoning damage.

19) Rhino Horn. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage.

20) Red Dragon Fire Breath. The abomination exhales fire in a 15-foot cone. Each creature in that area must make a DC 15 Dexterity saving throw, taking 24 (7d6) fire damage on a failed save, or half as much damage on a successful one.