Palinchron

An Illusion that keeps vanishing and reappearing, where the creature type and the combo loop describe the same act. The body is almost beside the point: blue players have never run this as a flier so much as a free spell that refunds its own mana. Cast it for seven and the enters trigger untaps seven lands, which means it pays itself back on arrival; the bounce clause completes the engine, handing you the return that lets you do it again. The loop only profits when those lands give you a surplus: eleven mana goes out across a full cycle (seven to recast, four to bounce), so the seven lands you untap need to produce twelve or more for the engine to net. That is trivial with high-output lands or a mana doubler in play, and from there the available mana climbs without ceiling, waiting for a single payoff to point it at. Urza's block ran a whole family of "free" spells that untapped exactly as many lands as they cost, balanced on the knife's edge of breaking even; Palinchron sits in that lineage but turns the recursion into the point rather than a one-time discount. Wizards has been wary of enters-untap effects on creatures ever since, precisely because the bounce ability hands you the recursion the free-spell template never intended. The card has never been a fair creature so much as a tolerated, well-understood combo piece.