Cloak of Invisibility
Mirage — Common
Enchanted creature has phasing and can't be blocked except by Walls. (It phases in or out before its controller untaps during each of his or her untap steps. While it's phased out, it's treated as though it doesn't exist.)
"Useful . . . if you can find it."
Pashad ibn Asim, Suq'Ata trader