You gain resistance to cold damage.

Any bite or claw attack you make gains an extra 1d4 necrotic damage. Damaging an enemy with you bite or claws grants you an abyssal token. When you get to three token you may use Call of the abyss.

Call of the abyss. Use your action to let out a powerful scream. Any creature within 15 ft. of you must make a constitution saving throw. On a fail the target takes 5d10 cold damage and they are considered vulnerable to next attack. On a success they take half damage. After the attack the area affected is covered in black ichor and is considered difficult terrain for anyone but you (and other rare creatures). The Ichor is effected by spells like control water and other water manipulation spells.