First off I'm not a hard core Blaster player, I've only got one at lvl 28 (Sonic/Energy) but I am a [BEEP].
Keep an eye out on the boss/lt when they fire an attack at the melee toon that's holding aggro fire up a nice heavy melee attack jump in an smack him then jump back/away try to break LOS even for a second. He's recharging and if he does aggro on you he's next to the tank/scrapper and will quickly be occupied again. Or he'll go ranged, which means he'll have maybe one attack then be distracted.
I know this is old advice but before firing your cones, back up. At least make an effort to max the number of targets in the cone. This of course applies to a preoccupied pile of aggro with a tank/scrapper making alot of noise at the center of the pile. If you break the tanks aggro, well you broke it, you've bought it.
Defenders can keep track of a fight, and their teammates health/end bars at the same time and so can you. If a defender or a controller is getting hit/mez'd take a few seconds to find the problem mob and kill it, or arrest it if you are feeling merciful. Remember a dead/mez'd defender or 'troller can't buff/heal you, or debuff/hold that pack of aggro that just developed ADD and is looking at you.
Having said that remember to cut and run if the fight is going south quickly. If you live you can get some brownie points by going back and feeding Awakes to the terminally inconvenienced, or sniping/killing the odd mob that's ALWAYS standing over the body of the one toon that can rez.
Know what you can do, know when you can do it, and do it. My Sonic/Eng knows that she can run in AM+BU fire 2 good attacks and maybe get BS at melee target. Also with PT/AS I can get out from any too amorous attention. However I get routinely told to hang back and don't melee. Oddly tanks and scrappers don't find this worth commenting on, it's the mother hen Defenders and Obsessive Controlling Controllers that freak. Bite me. If you can do and get away with it do it, and smile sweetly at the mother hens and think about them being force fed crow.
