Sparring Mummy

Point the entry trigger at a creature whose tap is its cost, and this becomes a one-shot reset: a mana dork fires twice, a tapper answers a second attacker, a pinger doubles its damage the turn it lands. That is the card's real job. The untap fires only on entry, with no option to decline and no repeat, so its ceiling is exactly what a single well-chosen untap is worth on the board in front of you. Note that "on entry" is not the same as "when you hard-cast it": the creature has no flash, but any effect that puts it onto the battlefield (a reanimation spell, a blink, a token copy) carries the trigger with it, and blink-and-return shells can turn a static reset into a recurring one. What the card cannot do is rescue a creature mid-combat off its own initiative, since the window is tied to its arrival rather than to a moment you choose. Timed for a second main phase, it can stand a tapped attacker back up to block, a pseudo-vigilance beat that is more incidental than central. This is a builder's piece rather than a threat: forgettable in isolation, a genuine tempo swing in a deck that already has a tap it wants to undo. The Zombie type and the modest white body slot it into go-wide and lifegain-adjacent shells where an extra blocker that also resets a key creature earns its keep.