No Spells

Appendage Strike. Melee Weapon Attack: +12 to hit, reach 5ft., 1 target. Hit: 20(2d8 + 8) Piercing damage. 

Extended Appendage Strike. Melee Weapon Attack: +8 to hit, range 10/20 ft., 1 target. Hit: 16 (2d8 + 4) Bludgeoning damage.

Special Attacks via Absorbed Parts - Dragon Appendages

• Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: (2d10 + 8) piercing damage plus (2d6)fire damage.
• Claw. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: (2d6 + 8) slashing damage.
• Tail. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: (2d8 + 8) bludgeoning damage.
• Fire Breath (Recharge 5-6). The dragon exhales fire in a 60-foot cone. Each creature in that area must make a DC 21 Dexterity saving throw, taking 63 (18d6) fire damage on a failed save, or half as much damage on a successful one.

Special Attacks - Giant Spider Appendages

• Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 7 (1d8 + 3) piercing damage, and the target must make a DC: 11 Constitution saving throw, taking 9 (2d8) 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.
• Web - Recharge 5. Ranged Weapon Attack: +5 to hit, range 30/60 ft., one creature. Hit: The target is restrained by webbing. As an action, the restrained target can make a DC: 12 Strength check, bursting the webbing on a success. The webbing can also be attacked and destroyed (AC 10; hp 5; vulnerability to fire damage; immunity to bludgeoning, poison, and psychic damage).

Form Shift: It can form a new limb or appendage based on a creature it has absorbed.

Creatures it has currently absorbed:

Adult Red Dragon, Giant, Gigantic Spider.

Malleable Form: As a reaction, the creature can shift it's form to avoid an attack that will hit.

Bonemold: As a reaction, Abomination can shift the hardness and thickness of it's flesh in order to give itself an additional +2 AC until it's next turn (can not be stacked; this can also be used to deflect an oncoming attack)

Can take 3 Legendary Actions, choosing from the options below. Only one legendary action can be used at a time, and only at the end of another creature's turn. Spent legendary Actions are regained at the start of each turn.

Detect: The Dragon makes a Wisdom (Perception) check.

Tail Attack: The Dragon makes a tail Attack.

Wing Attack (Costs 2 Actions): The Dragon beats its wings. Each creature within 10 ft. of the Dragon must succeed on a DC 22 Dexterity saving throw or take 15 (2d6 + 8) bludgeoning damage and be knocked prone. The Dragon can then fly up to half its flying speed.

None.