Arrow Volley Trap

Text:

If four or more creatures are attacking, you may pay rather than pay this spell's mana cost.
Arrow Volley Trap deals 5 damage divided as you choose among any number of target attacking creatures.

Rulings:

• 10/1/2009 You may ignore a Trap’s alternative cost condition and simply cast it for its normal mana cost. This is true even if its alternative cost condition has been met.
• 10/1/2009 Casting a Trap by paying its alternative cost doesn’t change its mana cost or converted mana cost. The only difference is the cost you actually pay.
• 10/1/2009 Effects that increase or reduce the cost to cast a Trap will apply to whichever cost you chose to pay.
• 10/1/2009 You divide the damage as you cast Arrow Volley Trap, not as it resolves. Each target must be assigned at least 1 damage.