Historical Rules · 29 April 2022
Rule 702.53a
Official source text from the 29 April 2022 Rules release
Transmute is an activated ability that functions only while the card with transmute is in a player’s hand. “Transmute [cost]” means “[Cost], Discard this card: Search your library for a card with the same mana value as the discarded card, reveal that card, and put it into your hand. Then shuffle your library. Activate only as a sorcery.”