Aphetto Alchemist

Untapping is the most quietly abusable verb in the game, and this is a clean repeatable engine for it. The tap ability resets any artifact or creature, which means it doubles whatever activated ability that permanent already carries: a mana rock taps twice, a creature with a tap-to-deal-damage clause fires twice, a tapper locks down two attackers instead of one. The restriction to artifacts and creatures is the real ceiling on the design; pointing the effect at a land or an enchantment is off the table, so the abuse has to run through a creature or rock whose tap cost is worth paying again. Within that lane the rate stops mattering entirely the moment you hand it a token-maker, a mana producer, or any tapper worth firing twice. The morph clause earns its keep beyond flavor: played face down, the disguised body hides which combo piece you are holding, so an opponent sequencing removal cannot tell the engine from a generic blocker until you have already spent to flip it. The 1/2 frame keeps it honest as an enabler rather than a beater; this is a card built to sit back and recur an effect, not trade in combat. It belongs to the lineage of untap-engine creatures whose whole job is to turn one useful tap ability into an arbitrarily large one, only ever as broken as the permanents you point it at.