Rune of the Archmage Team 5 never learns

Archmage robe flagged wrong slot ? :: The Elder Scrolls V arch mage slot To cast one of these druid spells, you must expend a slot of the spell's level or higher Mage of Witherbloom · Unearthed Arcana 79 archmage slot There is another Archmage robe in the Archmage room lying around on a table without the hood Then you can wear them both

archer slot game png I've red and re-red the description, and I see nothing preventing the Archmage to sacrifice spell slots from an other list than its primary