Xathrid Gorgon

Petrification is the mechanical pun this design is built around, and the activated ability is a quiet piece of removal that does something almost no other effect does: it neutralizes a creature without killing it. Dropping a petrification counter leaves the target on the battlefield as a colorless artifact that can't attack and can't use its activated abilities, which means it sidesteps the entire web of death triggers, recursion, and "leaves the battlefield" payoffs that make conventional removal a liability against the wrong deck. A Gorgon turning enemies to stone is flavor doing real rules work, and the choice to model that as a permanent lock rather than a kill is the whole appeal: it answers the indestructible threat, the must-not-die-on-board commander, the creature whose graveyard is more dangerous than its battlefield presence. Because the ability carries a tap symbol, it fires at instant speed once the Gorgon has shed summoning sickness, so a counter can land on an attacker mid-combat to shut down its future attacks and abilities. It is no answer to an ability already on the stack: petrify in response to an activation and the opponent still gets that effect; what you stop is every activation after it. The 3/6 deathtouch body is the slow part, a defensive frame rather than a clock, and tapping to petrify means giving up a blocker that turn. That tension files the card under toolbox rather than staple: the effect is unusual enough to matter, the rate slow enough to keep it from defining anything, and the result is a control piece that locks problems away one at a time instead of trading with them.