MTG >Combos >Card with Free Sacrifice ability +Crystalline Crawler +Mairsil, the Pretender +Endling +

Exile all cards with Mairsil Pay one black mana to give Undying to Mairsil Sacrifice Mairsil Undying's ability will trigger, return Mairsil to the battlefield Pay one mana and remove a +1/+1 Counter from Mairsil to add one black mana. Repeat the process for infinite ETB/Death Trigger