Although now I'm getting into the absurdly detailed, after having nearly every boss on farm mode I would like to explore the directional attack patterns for raid bosses.
We're trying to answer 2 parts to this question, special attack patterns and the more difficult to answer melee directional attack patterns.So, a good example is Arbanus. His attack pattern looks something like this...
General attack pattern: melee(10 seconds),unholy word(7 seconds),more melee(10 seconds),blood ritual(7 seconds), melee(10 seconds @ 50% or less health) occasionally skips this attack, blood draw(7 seconds).
Directional attacks: up, left, up, left, up, right (repeat). For melee attacks only.
Probably forgetting a couple things but that's the general idea for other boss fights you may want to discuss about. BTW, nearly all raid boss special attacks seem to be aoe based(non-directional), although I could be wrong about this.