Body of Flame. When an attacker attacks the Abyssal Wurm with a melee weapon attack that succseeds the attacker also takes 2d6+2 Fire Damage. This trait doesn't apply to magic melee weapons that do cold damage or radiant.

Duel Headed. The Abyssal Wurm has two heads Each of which can take their own actions. Their breath weapon is divided between the two of them.

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit:  (3d12 + 9) piercing damage. If the target is a Large or smaller creature, it must succeed on a DC 19 Dexterity saving throw or be swallowed by the worm. A swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside the worm, and it takes 21 (3d6) acid damage at the start of each of the worm's turns.

If the worm takes 30 damage or more on a single turn from a creature inside it, the worm must succeed on a DC 21 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the worm. If the worm dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 20 feet of movement, exiting prone.

Abyssal Calling. The Abyssal Wurm conjures a portal to the Abyss and summons either 1d4 demons of the DM's choice. These Demons then appear and start their turn on the tile of the portal. These Demons act on the Wurm's turn and aren't loyal to it unless they are CR 15 or higher and their are atleast two of them.

Breath of Fire. The Abyssal Wurm lets loose a deadly abyssal fire that scorches the earth. All creatures within a 60ft cone must succseed a DC 15 Dexterity saving throw or take 6d6+10 Fire damage or half as much on a succsees, Creatures with the Devil tag take double damage.