Cloak of Invisibility
Two distinct evasion ideas collide on one cheap Aura, and the collision is the whole story. Phasing was a Mirage-block keyword built for permanents that flicker themselves out of existence on a timer, dodging removal and combat alike on the turns they vanish; this staples that to a creature you actually want to attack with, on the cycles it phases in. The "can't be blocked except by Walls" clause is the older half of the design, a callback to a long line of unblockable-aside-from-Walls effects that predate keyworded evasion entirely. Bolting the two together produces a creature that is untargetable every other untap step and nearly unblockable when it isn't, which reads stronger than it plays: the phasing window is the friction. Your enchanted attacker is gone on the turns it phases out, and phasing carries the Aura along with it, so you are buying protection on the off-beats at the cost of tempo on the beats. The flavor lands cleanly, which is rare for a mechanic-heavy Aura: a cloak that makes its wearer flicker between visible and not, slipping past everything but the literal walls in the way. Few cards demonstrate so plainly what phasing was meant to evoke before the mechanic drifted toward purely functional uses in later printings.
