Xenic Poltergeist

Animating artifacts as creatures is a design well Wizards has returned to often, but this is where the well starts, and the shape of the ability is stranger than later iterations let on. Tap to turn a noncreature artifact into a creature whose body equals its mana value, only until your next upkeep: a repeatable animation that scales with the target's cost rather than printing a fixed body. The absence of any timing restriction is doing quiet work here. Because the tap ability carries no sorcery-speed clause, it fires at instant speed: leave the 1/1 untapped, wait for an opponent to commit to combat or tap out, then animate an expensive rock into a surprise blocker or finish a turn after attackers are declared. In a set built around artifacts that cost five, six, ten mana, that scaling clause is the whole pitch. Point it at the cheap utility rocks and lock-pieces and the resulting body barely matters; point it at the expensive ones and you have a 6/6 or 10/10. The cost is the catch. Three mana for a 1/1 that must survive to tap, with the animation lapsing at your next upkeep so you re-pay the tempo each cycle, asks the surrounding deck to protect a fragile body. Every later artifact-animator inherits this card's central question of which artifacts are worth turning sideways; most of them solve the fragility this one leaves on the table.