Kheru Spellsnatcher

Morph {4}{u}{u}

When this creature is turned face up, counter target spell. If that spell is countered this way, exile
it instead of putting it into its owner's graveyard.
You may cast that card without paying its mana cost for as long as it remains exiled.

"She was aflame with a sort of weird, pale-blue light that lighted up every nook and cranny of her."
- Alvin Schwartz