Historical Rules · 14 April 2023
Rule 702.71a
Official source text from the 14 April 2023 Rules release
Transfigure is an activated ability. “Transfigure [cost]” means “[Cost], Sacrifice this permanent: Search your library for a creature card with the same mana value as this permanent and put it onto the battlefield. Then shuffle your library. Activate only as a sorcery.”