Teferi's Honor Guard

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.) {U}{U}: This creature phases out. (While it's phased out, it's treated as though it doesn't exist. It phases in before you untap during your next untap step.)

"They may seem ceremonial, but their swords are still sharp." —Kipkemboi, Kukemssa pirate