Blade Dancer? If you’re looking for a damage-buff card and you’re debating whether to choose between Blade Dancer or Brawler, I’d suggest that you stick with Brawler until you can level up Blade Dancer to at least level 4. You want to hit the cap of 200% with as few kills as possible (or perhaps a fairer measure, is you want to equal or exceed the equivalent damage buff of your Brawler card in as few kills as possible). That said, many Escape players will say that Brawler isn’t that essential - the bleed from Venom Blade is strong, and the difference in time it takes for people to bleed out enemies with/without Brawler is very small for smaller Drone-size enemies.
Also I’d suggest you consider how many enemies you’ll be fighting. Blade Dancer works on the premise of you chaining together multiple melee kills (not hits) which increases your damage incrementally. Brawler gives you a straight damage buff which remains the same regardless. So as an example, for an Escape Hive like The Line, Blade Dancer isn’t going to be very useful because you only fight a small number of enemies (albeit, they’re all Scions so are individually very strong). You’ll probably fight them 2 or 3 at a time before you have to run off to your next fight and the damage buff you get from Blade Dancer isn’t going to last. However for The Warren as an example, you’re fighting LOTS of Juvies, so you will be able to easily chain together lots of kills to build up the extra damage.
In Horde it’s possible to use both Blade Master; and Brawler because the venom cards are obviously redundant so frees up card slots.