Nim Bannitlarn, Eldritch Mind

You may choose not to untap Nim Bannitlarn, Eldritch Mind during your untap step.
Banishment - {x}{u/b}{u/b}{t}: Exile up to two target creatures with combined converted mana cost X.
Those creatures remain exiled for as long as Nim Bannitlarn, Eldritch Mind remains tapped.
Insect Plague - {x}{b/g}{b/g}{t}: Create X 1/1 green
Insect creature tokens with flying. Exile those
tokens when Nim becomes untapped.