Phase Out / Banishing Smite

Phase Out: {w}{w}{w}{x}
X number of creatures you control gain Phasing.
Each turn pay X amount of mana,
if you don't, targeted creatures lose Phasing.
Eldritch Smite: {b}{b}{b}{x}
Target player's creatures with Toughness
equal to X are destroyed.
You can either Phase Out or Eldritch Smite
but not both