This clever loop relies on Technomancer and Phyrexian Metamorph entering and copying each other in an endless cycle. When Technomancer hits the battlefield, its entry trigger lets it pluck Phyrexian Metamorph right back out of the graveyard as a fresh copy of Technomancer. Before that new entry trigger even resolves, you use Lithatog to sacrifice the copying Metamorph, sending it back to the graveyard so it can be re-summoned all over again.