Magus of the Moat

Take an iconic enchantment, copy its text onto a Wizard body, and you change everything about how the effect can be reached. Moat was a four-mana white enchantment that read "creatures without flying can't attack," and it sat in the enchantment zone immune to most early-era removal, locking ground combat to a standstill. The text here is identical and symmetrical: nobody on the ground gets through, which means your own non-fliers are stalled alongside your opponent's. Building around it asks you to win in the air, with evasion, or with effects that don't depend on attacking. Re-skinning the lock as a 0/3 cuts both ways. The downside: it now dies to anything that touches creatures, where the original was harder to dislodge. The upside is why this version got printed at all. A creature can be tutored with creature-fetch effects, returned with creature recursion, flickered, and reanimated, none of which an enchantment could be. The body is incidental to the lock; the 0/3 survives most incidental pings, but the toughness is not what you are paying for. What four mana buys is a board-wide ground freeze that a whole separate set of tools can suddenly access. Among the Magus creatures that reprinted famous permanents onto Wizard bodies, this is the cleanest case study in the experiment: same effect, same cost, repackaged so creature-shaped tutors and recursion can finally find it.