Juniper, Spellstopper

Double Strike, deathtouch, lifelink
{3}, {t}: Counter target instant or sorcery spell
unless its owner pays {3}. If a spell is countered
this way, exile it instead of putting it into its
owner's graveyard. You may cast cards exiled
with Juniper, Spellstopper for as long as they
remain exiled, and you may spend mana as
though it were mana of any color to cast them.