You want enemies to all have good balanced skill bars and to use them intelligently? We have that mode already, its called PvP.
Actually, nvm, PvP has none of that anymore.
It's an ok idea, but I think it would be too hard to implement, too exploitable (think of the doppleganger), and too much of a pve style meta game. Either the builds are going to be nigh perfect counters to your build (think the worst kind of PvP metagaming builds + double damage/recharge/casting) or we would end up with every enemy in the game using almost exactly the same build.
I think any development time that just happens to be lying around would be put to better use just making enemies smarter then dogshit. Not to mention even if the enemies were perfect counter builds, I bet I (or at least someone else) could come up with a tank'n'spank build that relies on things that are completely uncounterable by pve enemies until we get an AI update that allows them to chose targets intelligently instead of going for either the nearest or training the monk. Shouts, weapon spells, and buffs without types could easily be an uncounterable wall, even without pve skills.
I think a more limited approach would be better, lets say all high end mobs get 1-3 wildcard skills on their bar that can be randomized between a number of different possibilites, but the 'core' 4-5 skills all remain the same. Gives every different mob a bit of originality, helps force people to be more reactionary instead of cookie cutter, and avoids some of the nasty possibilities that I outlined above. But above all else, we need better AI first. This is for all modes, not just this new uber mode, normal and hard mode desperately need these changes to make battles more unique. They also need the no pve skills/consumables changes, but lets not drag that discussion into this thread
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