I'm sure there's one around here somewhere. I've only read it a dozen times. Or was it two dozen?

The Scroll of Cautious Beckoning, when used in the proper communion ritual, will allow us to summon a specific Daedra and communicate as equals. It is a far gentler procedure than your standard Conjuration magic. I don't know of anyone that has such a scroll, but I suspect one was used in the great Daedric invocation at Tur Julan just a few decades ago.