Vampiric Frenzy

Vampiric Frenzy: If character hasn't consumed blood in: "1d6" days since last feeding player must make a constitution saving throw (DC 16) or be consumed by hunger and go on a rampage. Frenzy forces you to attack the nearest Humanoid or Beast. Frenzy ends when character has fed off of a creature and succeeds a constitution saving throw. If save is unsuccessful can reroll save upon feeding again with a +1 to their save. 

Multiattack. The vampire makes two attacks, only one of which can be a bite attack.

Claws. Melee Weapon Attack: +3 to hit, reach 5 ft., one creature. Hit: 8 (2d4 + 3) slashing damage. Instead of dealing damage, the vampire can grapple the target (escape DC 13).

Frenzied Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., a creature that is grappled by the vampire, incapacitated, or restrained. Hit: 6 (1d6 + 3) piercing damage plus 7 (2d6) necrotic damage. The target's hit point maximum is reduced by an amount equal to the necrotic damage taken, and the vampire regains hit points equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0.