I like the idea of the chain attacks, but it won't work out in practice. There was a similar system in Dark Age of Camelot, where certain attacks would chain off each other. In practice, pulling off those chains in a PvP setting was nearly impossible. The end result was that it was either not worth it to try, so you'd only use the opening attack over and over, or the finishing attack was so powerful that the fight was essentially over if you pulled it off. The latter, you could argue, is fine, since it took so much skill it maybe SHOULD end the fight, but then it would be overpowered in PvE where it was much easier to pull off. The best way to fix that would be to prevent chains from "breaking" either due to dodges/parries or time between attacks, but then you still have problems that WoW brought to light - specifically, that this is essentially a rotation and isn't really how Blizzard likes to design classes anymore. That's assuming that the "chain" doesn't all have to be on one target, so you're avoiding the Rogue problem with having to switch targets when all your combo points are on the guy you aren't supposed to hit anymore. Long story short, the chain mechanic is problematic. It's not impossible, but ultimately I don't know that it's worth it. I'd recommend something more like a resource system.