Pendant of the Life Drinker

wondrous item (necklace), rare, requires attunement
 
  This velvet pendant was crafted by cunning vampires to make mortals succumb to the appeal of the exquisite delight that is blood.
 
  When attuned to this necklace, you become capable of draining the life of your foes. You can replace one of your melee attacks by a fang attack. Make a melee weapon attack using your Strength or Dexterity, on a hit this attack deals 3d8 necrotic damage and you regain a number of hit points equal to the necrotic damage dealt.
  Once per day, when you should fall to 0 hit points or lower, you can use your reaction to make this attack.
 
  Curse - Blood Call:
  After feeding more than 3 times on blood in a day you must succeed on a DC 12 Wisdom saving throw or fall into blood lust for the next 8 hours. Each time you feed on blood after that, the DC increases by 3. When you finish a long rest, it resets.
 
  While blood lusted you fall under your GM’s control and become a bloodthirsty beast with no recognition of friends of foes. Only feeding on blood matters to you. During that period you attract vampires within a 3 miles radius which will try to turn you into one of them. If you survive this curse without becoming a vampire or thrall, the pendant loses all power.