Well First step is to pump up your dps, if your getting more then flame shards, you need to try harder. You can do it with NO Shard adds...its timed.
enflamed adds - Nuke with 1 fire nuke, then cure the dot/ae heal.
Arcane- Have Knights TAUNT only, We root them? Just make sure its a chomatic root(ranger or druid iirc, might be the enc knockback thing)I think Just make sure NO ONE cast magic spells on them or they blow up for 40k.
Icy- Been a long time since i've seen these... Ice nukes slow the aoes, we tanked them and killed them with bl's and wizards(ice nukers) If your getting them you'll need basicly constant ae heals to survive.
Finally the longer it goes on the "bigger" the shards get. A larger looking enflamed shard of brath no longer takes 1 fire nuke to kill but 3 iirc. And so on. But, as I said, We do it with 0 or only a set of flame adds.