Ifwas spent to cast River's Grasp, return up to one target creature to its owner's hand. If was spent to cast River's Grasp, target player reveals his or her hand, you choose a nonland card from it, then that player discards that card. (Do both if was spent.)
5/1/2008 The spell cares about what mana was spent to pay its total cost, not just what mana was spent to pay the hybrid part of its cost.
5/1/2008 The spell checks on resolution to see if any mana of the stated colors was spent to pay its cost. If so, it doesn't matter how much mana of that color was spent.
5/1/2008 If the spell is copied, the copy will never have had mana of the stated color paid for it, no matter what colors were spent on the original spell.
5/1/2008 When you cast the spell, you choose its targets before you pay for it.