Warden of the Beyond

The +2/+2 is static, not a trigger: as long as any opponent owns a card in exile, this Wizard stands as a 4/4 with vigilance, and the instant that condition lapses it shrinks back to a 2/2. The clever part is how reachable the condition is despite the hatebear flavor: exile shows up constantly as a byproduct of ordinary play. White already leans on exile-based removal, so your own answers do most of the lifting. Point Path to Exile or Banishing Light at an opposing creature and that card sits in exile under its owner, with the buff arriving for free. The reward comes from interacting the way you were going to anyway, not from folding your deck around a parasitic mechanic. The genuine cost is swinginess: against an opponent who never sends a card to exile, and with no exile-based removal of your own to aim at them, you have a vigilant 2/2 and a dormant clause. That dependence on exile existing somewhere on the table is the restriction holding the rate in check. What makes it a cleaner conditional beater than most is that the payoff arrives as collateral from your own removal instead of a switch you flip: the buff is a passive read of the board, and the creature never stops needing the right opposing card sitting in exile to reach its best size.