Spire Patrol

The body is the giveaway: a 3/2 flier for four mana is a hair below the rate you'd want from a pure beater, and that shortfall is paid back by the enters trigger, which is the real reason this slot exists. Tapping a creature and denying it the next untap is a two-turn Frost Titan-style lockdown stapled to a flier: you remove a blocker on the swing that matters, then the same creature sits useless through your opponent's following turn, so the tempo swing lands on both the attack you make now and the defense they cannot mount next. The flying body keeps pressing while the lock holds, which is how a removal-adjacent effect on a creature converts into clock rather than just parity. The design lineage runs through every white-blue tempo flier that wraps a board-interaction trigger around an evasive body, where the creature is both the threat and the answer in one card and the enters effect is what justifies the soft stats. Note the limit that keeps it honest: the tap targets a creature an opponent controls, so there's no using it to untrigger your own vigilance shenanigans or to set up combat in a mirror, and the effect ends after one missed untap rather than locking the permanent down for good.