Trivia Questions, ED (Horrors) in the 6th Age Options

[FiveVenoms]

I was curious about the ED phenomenon known as the Horrors. I don't particularly remember anything about EarthDawn, other than sooner or later, The Horrors show up in a given "mana cycle", screw over everybody, and thus goes into the 3rd/5th/etc. Age. If I recall correctly, Dunkelzahn was pretty big on preventing this cycle of events somehow.

I've been recently trying to keep track of the "top dogs" of the SR Setting, and realized that however often they're mentioned, I really know nothing much about the Horrors. Are they more powerful than elves and dragons? Are they gibbering demons with no discernable motives from beyond the realms of human comprehension, or is "Horror" a vague classification? For that matter, are there a finite number of them, like the "Well known" Great Dragons? Is there Bob the PanDimensional demon mage, as well as Yxgrathl the Cthulu-esque abstract deity of destruction? That is to say, are some relatively anthropomorphic bad-asses with more material plans in mind, and others are crazed abstract forces of destruction, or are all Horrors basically nihilistic demons of various categorizations? Does anybody know how far into a Mana Cycle they appear (mana spikes and Harlequin novels notwithstanding, that is-although I have no idea what that was all about either)?