Spelljack

Counter target spell. If that spell is countered
this way, exile it instead of putting it into its
owner's graveyard. You may play it without
paying its mana cost for as long as it remains
exiled.
"When raiding, it's important to hoard all that
you can, intelligence can be a powerful weapon
down the line for those that know how to use it."
—Second Mate, Breeches