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

The List

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}: Teferi's Honor Guard 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.)

Visions

Flanking (Whenever a creature without flanking is assigned to block this creature, the blocking creature gets -1/-1 until end of turn.)
o
Uoo
U Phase out