Eldritch Immunity

Target creature you control gains protection from each color until end of turn.
Overload {4}{C} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Selective Obliteration

Each player chooses a color. Then exile each permanent unless it's colorless or it's only the color its controller chose.

Null Elemental Blast

Choose one —
• Counter target multicolored spell.
• Destroy target multicolored permanent.

Marvin, Murderous Mimic

Marvin, Murderous Mimic has all activated abilities of creatures you control that don't have the same name as this creature.

Echoes of Eternity

If a triggered ability of a colorless spell you control or another colorless permanent you control triggers, that ability triggers an additional time.
Whenever you cast a colorless spell, copy it. You may choose new targets for the copy. (A copy of a permanent spell becomes a token.)