Illusionary Wall

A wall that hits back, on a body that betrays the entire premise of its type. Defender pins it to the back rank, but flying and first strike turn it into a blocker that wins fights it has no business surviving: a 7/4 that strikes before almost anything in the air can answer, then sits there absorbing the next attacker. The body and the keywords are pulling in opposite directions on purpose. The 7/4 is oversized for any creature that cannot attack, the flying makes it a defensive answer to a whole axis of threats, and the first strike means it trades up rather than across; the result is a wall priced like an attacker that does everything but attack.

Cumulative upkeep is the leash. Designers of this era used the mechanic as a self-correcting power tax: a permanent this efficient at holding the ground should not stay free, so each turn it demands one more blue than the last, until the wall you were happy to keep becomes the spell you cannot afford to keep. That decay is the entire balancing act. The card asks how many turns of an oversized first-striking flyer-blocker you actually need, then prices every turn past that point in escalating mana. Read against modern defensive creatures, the rate is absurd and the maintenance is brutal, which is exactly the trade the mechanic was built to enforce.