So as some of you may know there is a combo with Archfiend of Dross and Metamorphic Alteration.
Some of the ways I know to stop the combo is killing the creature that is being targeted by Metamorphic Alteration, giving the creature hex proof/shroud, sacrificing the creature, countering the metamorphic alterations, giving that creature more oil counters (lol)
But does killing/sacrificing the Archfiend in response to the Metamorphic stop it?
Metamorphic says choose not Target. So I'm not sure.
If Archfiend is killed before Metamorphic Alteration enters the battlefield, Alteration will still enter, you will just need to choose a different creature for the enchanted creature to become a copy of. This usually isn't all bad - turning a Sheoldred into, say, a 1/1 Pilot token, has won me some games before!