Originally Posted by
Shurrikhan
One more consideration:
I mentioned before that the activation cost for Darkside is a critical consideration, but I don't think I emphasized that quite enough. It go anywhere from feeling passive (just always leave Darkside on) to feeling a ridiculously and convoluted gimmick (MP-/server-tick gaming) on the basis of MP cost and ICD.
Moreover, consider what that passive MP drain does to APM if you want/have any other way to spend MP. Is just maintaining your damage buff really any more interesting than, say, 3.33 charges of oGCD attacks (onto which you could attach whatever other interesting effects, too)? I would think not; I'd personally keep a reinvigorated Edge/Flood or Dark Arts over or atop (increasing MP gen, then, to compensate) that Darkside.
For a constantly resource-consuming stance, then, to feel like it's adding gameplay rather than acting as a constraint on the gameplay otherwise possible, you need it to be more worth toggling the stance on and off optimally than to simply increase or decrease the rate of other spenders.