Carnage symbiote

Piercer. Once per turn when the symbiote hits with an attack that does piercing damage it can re-roll one of the die and chooses the better result. On a critical hit with piercing damage the symbiote rolls an extra damage die when determining the piercing damage.

Bite. Melee Weapon Attack. 1d20+10 to hit. 10ft range.1d8+7 piercing damage. If this would bring a target to 0 hitpoints the symbiote eats the target's head off adding a single die type equal to that creature's die type to the symbiote's damage. (You do not continuously add the die to the roll, you simply roll it once and the result will be added to the damage).

Tendrils. Melee Weapon Attack. 1d20+5 to hit. 20ft range. 1d8+10 piercing damage and 1d6+6 poison damage.