Kaijin of the Vanishing Touch

A blocker that doesn't just stop an attacker but undoes the turn it spent getting there. The 0/3 body parks in front of a single ground creature, and at end of combat that creature returns to its owner's hand: a tempo tax that forces the attacker to re-pay the mana sunk into casting it. The key to the design is when the trigger locks in. The delayed bounce is created the moment the block is declared, so it resolves at end of combat no matter what happens during the damage step. Kill the Spirit with the attacker and the attacker still goes home anyway; the trade can never net the attacker a clean kill that keeps the body on board. Size never matters to the return, either: a creature well past three toughness can punch through and drop the Spirit in the graveyard, but it still bounces at end of combat, so even a one-time chump resets a threat the wall could never trade with on stats alone. Three toughness lets it survive most cheap early bodies and repeat the trick, earning its keep against ground aggression leaning on vanilla creatures. The same return clause cuts the other way, though: block something with an enter-the-battlefield trigger and you've handed the opponent a free recast with the trigger primed to fire again. And the one door it never closes is the sky. Fliers route around a wall that can only stop what agrees to be blocked.