Oracle Text

Counter target spell unless its controller discards his or her hand.

Transmute 1UB (1UB, Discard this card: Search your library for a card with the same converted mana cost as this card, reveal it, and put it into your hand. Then shuffle your library. Transmute only as a sorcery.)

Card Rulings

10/1/2005 If the spell’s controller has no cards in his or her hand, that player can still choose to discard his or her hand and prevent the spell from being countered.