The Action of the Mi-Go Scalpel reads: "Exhaust Mi-Go Scalpel to have attached character gain an icon of your choice for each of your Mi-Go characters in play until the end of the phase." This had led to some debate amongst my group of players. Does the text indicate that you get to choose a different icon for each Mi-Go in play, or do you choose one icon type (such as terror) and all icons granted are of that type? The text could be interpreted either way.

The latter is correct.

Phantom287 said:

The FAQ addresses this about the Soothsayer:

If there are two attachments in play, can Soothsayer (Secrets of Arkham F10) gain two different icons, say a terror and a combat, or does she only gain the same icon regardless of the number of attachments in play?

Soothsayer reads, “Response: After Soothsayer commits to a story, Soothsayer gains an icon of your choice until the end of the phase for each Attachment card in play.” It allows you to choose a single icon and then it gains one instance of that icon for each Attachment card in play.