Fury of the Horde

If you don’t have two cards of the right color in your hand, you can’t choose to cast the spell using the alternative cost.

You may pay the alternative cost rather than the card’s mana cost. Any additional costs are paid as normal.

If it’s somehow not a main phase when Fury of the Horde resolves, all it does is untap all creatures that attacked that turn. No new phases are created.