Incubation Triformer is a rare Creature — Phyrexian Cleric card from Unknown Event (UNK), collector number RB03c. Current market price: $0.24, TCGplayer market prices via Scryfall.
When Incubation Triformer enters the battlefield, incubate 1. {3}: Choose target transformed Phyrexian token you control. Transform it into a third side that's a 3/3 Phyrexian Horror artifact creature.