Mistcaller

A one-mana hate bear built around a single verb: enter. Reanimation, flicker payoffs, and every cheat that puts a creature onto the battlefield without paying its cost share one weakness, which is that the creature has to arrive rather than be cast. This turns that arrival into a kill switch. The sacrifice clause turns a static lock into a one-shot trap: you hold up a 1/1, then spend it at the exact moment an opponent commits to a reanimation spell or a blink engine's centerpiece, and for the rest of the turn any nontoken creature that would enter without being cast is exiled instead. The "wasn't cast" qualifier is the precision instrument here. Creatures that pay their mana cost and resolve off the stack walk in untouched, so it never punishes fair play; it punishes the shortcut, and exile rather than destruction closes the door on graveyard recursion. The "nontoken" clause draws the other boundary: token generators and populate strategies fall outside its reach entirely, because those never produce a card that "wasn't cast" in the relevant sense. That narrows it to a clean answer for cheating creatures into play, not for going wide. As hate pieces go, it is unusually deferred: the body sits on the board doing nothing until the precise turn the matchup asks it to detonate, at which point one blue mana of investment erases a whole plan.