If
![Blue](/Handlers/Image.ashx?size=small&name=U&type=symbol)
was spent to play River's Grasp, return up to one target creature to its owner's hand. If
![Black](/Handlers/Image.ashx?size=small&name=B&type=symbol)
was spent to play 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 ![Blue](/Handlers/Image.ashx?size=small&name=U&type=symbol)
was spent.)