This clever loop spins a closed-loop engine out of life payments and graveyard recycling, perfectly facilitated by Tormod, the Desecrator's watchful eye whenever a card departs your graveyard. By paying 3 life to pull Cleaving Reaper back to your hand, you trigger Tormod to spawn a Zombie token, which immediately feeds into Phyrexian Altar to generate the white mana needed for Peace of Mind. You then use that exact mana and discard Cleaving Reaper to Peace of Mind—recouping the 3 life you spent while neatly sliding the Reaper back into the graveyard so the whole cycle can begin anew.