Unfortunately, ever since Storm Legion launched, Bladedancer has become more and more overshadowed by other builds. There have been changes that have helped to mitigate this, like the increase to Duelist Pose's duration and the buff to Fated Blades, but they haven't been enough for it to keep pace with the other rogue DPS builds.
It's a shame for such a fun soul to be so uncompetitive, so let's take a look at its problems and how to fix them.
The first problem is pretty straightforward: Bladedancer's DPS just isn't very good. It's barely even better than Marksman on a raid-buffed training dummy, and MM is a ranged soul, so it pulls ahead whenever Bladedancer has to move out of melee. BD does have good AoE, but only within very specific time windows, and it's not sustained AoE, so the one thing it's specialized for is too narrow to be much of a redeeming factor.
The second problem is range. Unlike Nightblade, Bladedancer doesn't have any ranged attacks to help with disconnects. Unlike Assassin, it doesn't have bleeds that allow sustained DPS even when out of range. You can pick up Fiery Spike or Quick Shot, but neither one benefits from Fated Blades, Dualism, or Double Coup, and they can't proc Duelist Pose, either. Also, disconnects during Fated Blades and Dualism are crippling-- unlike many specs that rely on attacks with short cooldowns, Bladedancer relies on strong attacks during cooldowns, so spending some of that duration out of range is a huge loss. To top it off, Bladedancer still suffers from a highly irritating bug where mainhand attacks on moving targets will occasionally fail to activate offhand attacks.
The last problem is utility. Bladedancer doesn't really bring anything a raid needs-- it's competing with Nightblade for the spot of "rogue melee with ST and AoE", and Nightblade tends to win by default because it has ranged attacks.
So, the solution.
First off, Bladedancer could really use a buff to single-target DPS. How this is done doesn't matter a whole lot, although I think that buffing Duelist Pose is probably the simplest way.
To address the second problem, I actually don't think that giving BD a ranged attack is the right answer. Instead, I propose adding a new talent. One that makes it so that for couple seconds you spend not attacking while a dance is active, you get a stacking damage buff for your next offhand attack. Maybe 15-20% per stack, up to a max of 3 stacks, possibly with a small crit chance buff tacked on to help refresh Hack and Slash/DP/Magnify Pain. Just enough to give you a bit of damage back after you're forced to run out, to simulate the way that Assassin would be able to take advantage of a Backstab that had come off cooldown or Nightblade could leverage the extra energy regenerated.
For the third... well, Dauntless Strike is the solution, in my opinion. Right now, the only souls that can provide the 5% crit debuff on the target are Assassin and Champion. Champion doesn't see much use anyways, and Assassin doesn't need Lethal Poison to be worthwhile. The simple fact that it has the highest ST DPS out of all the rogue souls is enough. If Dauntless Strike were changed to apply the 5% crit debuff instead (or just make it apply passively from all Bladedancer finishers), then BD would have something to set it apart from Nightblade.
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