Effectual Struggle

As an additional cost to cast this spell, tap a green or white nonland permanent you control.
Destroy target enchantment or creature with a converted mana cost of 5 or less.
{1}{r}{g} Flashback (You may cast this card from your graveyard for its flashback cost. Then exile it.)
"I trust there remaineth an effectual struggle to be
made." --King Limhi