Great points above, although of course you will want to be able to use your cross class slot on something a bit less redundant than Flash later.

If you are tanking a pack that does not need stuns, go ahead and use Brutal Swing in your rotation, and be sure to take advantage of Mercy Stroke when a mob's health falls low enough. I think you already mentioned cycling targets with your BB combo, which is good. You can also play around with seeing if you can get away with using Overpower slightly less in the front end of your pull, using it or flash after a few combos if you still see your party members catching up with you on the meters. Using Unchained when available can help you with enmity as well.

Honestly I wish we had a TP regen available to us in Defiance, because I never run out of TP in Deliverance, only when I need to be in Defiance to keep up with enmity...