Heirloom Mirror // Inherited Fiend

The design problem here is how to make a slow, incremental payoff feel earned rather than punishing. Before it flips, this is a repeatable rummaging engine that charges itself: every activation swaps a card, mills one off your library, and inches a ritual counter toward three, at which point the artifact transforms into a flying beater that eats graveyards for growth. What keeps the loop honest is the tax you pay to run it: mana, a tap, a life point, and a card from hand, all at sorcery speed. That is a lot of friction for what is, in hand, a strictly card-neutral trade (discard one, draw one), and it means the flip is never free; you are spending real resources across three turns to buy a flier that then demands more black mana to grow. The self-mill is the clever wrinkle: it seeds the transformed side's graveyard-exile ability while you are still assembling the counters, so the card quietly builds fuel for its own second mode. Transforming permanents that ask you to prepay their cost over multiple turns are a recurring flip-card idiom, and this one lands on the patient end of that spectrum: a card-selection engine that eventually becomes a threat, rather than a threat that filters as a bonus. The demon it becomes is modest by the standards of what usually crawls out of black graveyards, but the point was never the body. It is the loop that gets you there.