River's Grasp is a uncommon Sorcery card from Shadowmoor (SHM), collector number 174. Current market price: $0.20 (foil $0.51), TCGplayer market prices via Scryfall.
If {U} was spent to cast this spell, return up to one target creature to its owner's hand. If {B} was spent to cast this spell, target player reveals their hand, you choose a nonland card from it, then that player discards that card. (Do both if {U}{B} was spent.)