Unless we start seeing significant room for utility, I actually have little to no interest in seeing Dark Arts returned, though that has mostly to do with the skill being a "buff next action" more so than the ability to spend MP to augment actions. The latter bit I like, and I certainly prefer that over just the "Deal ST or AoE potency" of Edge/Flood. But, I just don't see the point in (A) basic buffs nor (B) reducing action responsiveness by using a "buff next action" skill instead of a "capitalize on last action skill" follow-up skill, especially given that the second can easily reduce button-conflicts, allow for tighter timing control, and generally allow for a more varied additional effect than can the buffing approach. It allows us, for instance, to just hit the CD's button a second time to follow up on it, with a discrete button being used only for our CD-less actions / GCDs.
Want to DA an Abyssal Drain as to steal further life over time (with, of course, the more immediate burst heal remaining on the initial button-press itself)? Just hit Abyssal Drain a second time within 5s or so of the original cast. Want to DA your Carve and Spit in order to tear off a few chunks of your enemy's soul for <some utility-minded effect with a bit of potency of potency per MP equal to all other DA options>? Just hit Carve and Spit a second time within 5s or so of the original cast.
