Transmute Artifact + Su-Chi

[psly4mne]

Now that the sacrifice for Transmute Artifact happens on resolution, does that mean it is impossible to sacrifice Su-Chi and use Su-Chi mana to pay for the cost of the artifact you search for?

[Daenyth]

That sounds right to me. The triggered ability wouldn't go on the stack until after transmute resolves

[Mantis]

Transmute Artifact requires you to sacrifice an artifact as part of the manacost. The stack will end up looking like this: top Transmute Artifact, bottom Su-Chi. Thus, Su-Chi will add 4 mana and then Transmute Artifact will resolve and the pay X clause is not part of it's manacost.

Short answer: Just Su-Chi and Transmute Artifact without any additional mana paid, can get you an artifact of 8 mana.

[psly4mne]

Matis, Transmute Artifact was errata'd recently. The sacrifice is part of the effect now.

[vartemis]

Transmute Artifact
Transmute Artifact includes a word not found on any other printed Magic card: "fails." This gives it some street cred for being unique and qualifies it for several Internet blogs, but makes figuring out what this card is supposed to do without context that much more challenging. Sacrificing the artifact used to be part of the cost, but that doesn't jive with what we believe the intent of the printed wording was. You shouldn't have to sacrifice the artifact if Transmute Artifact is countered, for example. However, we also believe that searching your library should be contingent upon the sacrifice. And we're taking "fail" to mean the searched-for artifact card never makes it onto the battlefield if you have to pay the difference and don't. Rules management is often more art than science.

New wording
Sacrifice an artifact. If you do, search your library for an artifact card. If that card's converted mana cost is less than or equal to the sacrificed artifact's converted mana cost, put it onto the battlefield. It it's greater, you may pay {oX}, where X is the difference. If you do, put it onto the battlefield. If you don't, put it into its owner's graveyard. Then shuffle your library.