This clever loop relies on Ulasht, the Hate Seed's ability to trade its own counters for bodies, which we then feed directly into Phyrexian Altar to generate the exact mana needed to keep repeating the process. As those tokens perish in the Altar, Long Feng, Grand Secretariat watches the graveyard and continuously rewards Ulasht with fresh +1/+1 counters to replace the ones we spent. Because the mana generated by the Altar pays for Ulasht's activation cost and leaves you right back where you started in terms of counters, you can cycle this sequence as many times as you desire.