Are devils worth 7 blood each?

[Cohen]

Usually are Pythium and Arco that use that spells.
Sometimes the nations that have 2S mages + a random pick, like Abysyan warlocks.

Usually you need a +1 S item however.

If an Astral Mage is in the targetted provinces, you'll get all your mages feebleminded AND the spellcasting will be aborted, so you can't kill anyone.

Personally I believe it's pretty weak that 1 single 1 S mage could feeblemind mages far better than him and more numberous. (according to description 1 lvl in a path means normal user, 2 lvls mean good mage in that path, 3 or more a very powerful mage of that path).