Ruin Snakes also regenerate (1d12+4) hp from acid per turn at the beginning of their turn.
When this creature goes to 0 hit points, the ruin snake may roll a con save (DC = 10 - Goes up by 2 every time it dies.) Regains health equal to three times the amount rolled above the DC. So if DC is 10, and the snake rolls a 13, it gets back up with 9 HP.
Multi-attack: Can use a Bite and Tail attack on it's turn.
Bite: +9 to hit, 10 ft Reach. Deals (2d12+6) Piercing damage + (2d6) Acid damage. If a creature is Medium or smaller, it is grappled. DC 15. Until this grapple ends, the creature is restrained, and the Ruin Snake can't bite another target.
Tail: +9 to hit, 10 ft Reach. Deals (2d6+6) Bludgeoning damage + (2d6) Acid Damage.
Acid Spit: +6 to hit (Auto-hits if you are grappled by bite), 60 ft. Deals (3d12+3) Acid damage.
May may an AOO with disadvantage even if a creature disengages.