I don’t know!
I thought about “builds for each skill as main skill” but that would be either over really quickly… or impossible to do, depending on how you put the parameters. (I’ve never really seen a build using Inquisitor seal as the main attack, for example)
Also thought about “A pet build for every class”… but I’m sure @Maya and @Skelemental have already done that between them.
“AA for every damage type” is also probably already done.
“Single mastery builds” have been done as well…
One facet of this game that hasn’t been explored that much (Perhaps because it’s underwhelming) that I like is DoT damage, and how to build around it and optimize it fully. But there isn’t enough material there for a collaborative thread like this one, I’m afraid.
“Faction gear only build for every class” sounds like a nice challenge too, but would also be over very quickly. (Though that might be the best one of the lot so far)
“Use every set not for it’s main damage type or class” (Like Bleed Korba, or my Blood Knight Dervish)
I’m stumped. I wish I had an idea for one such cool group project, but right now I got nothing.