Balor

The monster explodes when it dies.
Dexterity Saving Throw: DC , each creature in a -foot Emanation originating from the monster.
Failure: damage.
Failure or Success: If the monster dies outside the Abyss, it gains a new body instantly, reviving with all its Hit Points somewhere in the Abyss.

At the end of each of the monster's turns, each of the monster's choice in a -foot Emanation originating from the monster takes damage.

If the monster fails a saving throw, it can choose to succeed instead.

The monster has Advantage on saving throws against spells and other magical effects.

The monster makes one attack and one attack.

. . If the target is a Huge or smaller creature, the monster pulls the target up to 25 feet straight toward itself, and the target has the Prone condition.

. , and the target can't take Reaction until the start of the monster's next turn.

The monster teleports of itself up to feet to an unoccupied space the monster can see.