Lore:The Origins of Conjuration
Imperial mages have arguably advanced the study of conjuration magic far more than most, but it first fell to Elven wizards to crack open the door to Oblivion without its screaming horrors spilling uncontrollably into Mundus. Corvus and Calani Direnni and their clan first lit the torch and peered into this unholy darkness, lighting the path for the magical school of conjuration. Their precise binding chants are still used to this day when summoning lesser Daedra.
Nonbelligerent atronachs offered something of a boon to Clan Direnni, acting as protectors and occasionally servants or familiars. Even the naturally mischievous imp was easily coerced into behaving. But one can always count on the natural curiosity, and almost calamitous pomposity, of the Elves, who swung the door open still farther—a door to the Daedric planes that became impossibly difficult to shut.
Late into the First Era, Direnni acolytes first attempted to cajole enthrallment from Greater Daedra. Although the most skillful of conjurers succeeded reasonably against these chaotic agents, some Elves were weak, and the portal to Oblivion can now never be completely sealed. Subsequent catastrophic confrontations with Daedric princes turned our lands to turmoil. Thus, it falls to every mage in Cyrodiil to actively dissuade traffic with the Greater Daedra in the strongest possible manner. Communion with them is strictly forbidden.