Jeskai Barricade

A defender is supposed to sit still and absorb damage, but the flash makes this one ambush at the worst possible moment: cast it during an opponent's attack and you get both a 0/4 to soak a hit and a bounce of one of your own creatures, mid-combat, at instant speed. That bounce is the real engine. Returning a creature you control resets enters-the-battlefield triggers, and doing it on the opponent's turn turns the wall into a recursion piece rather than a pure blocker. A blink target with a strong entry effect gets to fire twice while you also untap with a fresh body in play; a creature about to die in combat or to removal gets saved instead of bounced uselessly. The 0/4 body and Defender keyword set the price for that flexibility: this is not a clock, it never attacks, and the return is optional and targeted at your own side, so it cannot disrupt the opponent directly. What it does is fold a value reset and a defensive wall into a two-cost flash spell, which is a tighter package than the rate suggests. The design rewards a board built around entry triggers, where the wall is less a wall than a button you press at the end of the opponent's turn to rebuy whatever your best creature does when it lands.