This clever loop turns Ashnod's Altar into an infinite colorless mana engine by exploiting a clever copy interaction. You cast or copy Vesperlark so that Phantasmal Image can enter the battlefield as a precise replica of it, setting the stage for perpetual sacrifice. When you feed that copied Vesperlark to Ashnod's Altar, its leaves-the-battlefield trigger fires off, pulling the original Vesperlark—or another eligible card—right back from the graveyard, ready to sustain the cycle.