Prison Barricade

Defender is usually a one-way contract: the creature can't attack, and nothing about it ever changes that. Kicker rewrites the deal as you cast the spell. Pay the base and you get a 1/3 Wall that holds ground; pay the surcharge and the same card arrives as a 2/4 carrying a +1/+1 counter and a clause that overrides its own defender, letting it swing. The choice locks in before the card ever resolves: this is not a creature you play cheap and upgrade later, but one whose mode you commit to up front, weighing whether the board wants a blocker now or a modest attacker for the full investment. The design idea worth noting is that defender need not be permanent, and that the permission to attack can be written onto the body itself rather than granted by an outside effect. Either configuration is deliberately unspectacular: the unkicked side is a cheap stall, the kicked side a slightly oversized body that has paid two mana extra to take a turn off defense and pressure life totals. What it offers is a single card that answers two different questions depending on the mana available and the shape of the game, without pretending to dominate either plan.