Transmute Question

[Kudd]

Is transmute an activated ability?

The question is due to this: can 'transmute' be stopped? i.e. stifle

[Michael Keller]

Is transmute an activated ability?

The question is due to this: can 'transmute' be stopped? i.e. stifle

From the Comprehensive Rules:

* 502.48. Transmute
o 502.48a 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 converted mana cost as the discarded card, reveal that card, and put it into your hand. Then shuffle your library. Play this ability only any time you could play a sorcery.”

[mchainmail]

Transmute 1BlueBlue (1BlueBlue, Discard this card: Search your library for a card with converted mana cost 0, reveal it, and put it into your hand. Then shuffle your library. Transmute only as a sorcery.)

There's a colon; it's an activated abiliity.