The Bloodsky Massacre [KHM-207]

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — Create a 2/3 red Demon Berserker creature token with menace. II — Whenever a Berserker attacks this turn, you draw a card and you lose 1 life. III — Add {R} for each Berserker you control. Until end of turn, you don't lose this mana as steps and phases end.