I've got a bad
habit of saving Mirror Image as an agro drop, but it is a DPS cooldown,
and if you're raiding, it should be used on cooldown. If the
big-and-ugly is on the squishy mage, then odds are the raid is in
trouble anyway.

for the uninitiated, Invisibility does take 3
seconds to completely drop agro. Any damage will kick you out of it, and
any healing received can put you back on the agro table. I hate to say
it, but if the raid leader calls for a wipe, rogues and hunters are
better able to live for the mass rez.Flame Strike, is weak on its own. Couple with Blizzard or Arcane Explosion. Or better yet let the warlocks handle trash.

Lastly,
but not leastly, Dragon's Breath has a daze, but it can also interrupt.
I use it to great effect on Garrosh during non-empowered mind control.
The daze doesn't last long with the raid beating on the traitors, but
it's quite nice interrupting 3 casts with one spell. Unfortunately it
doesn't work on empowered, and you have to use Counterspell. Flamestrike is pointless to cast unless you can do it before you can
be casting other spells. Norushen is the only fight that I cast it on,
and that's only because you can't precast a Pyroblast into the boss.Also,
Mirror Images do very little damage, so while you do get a tiny bit
more dps from them, saving it to drop aggro is totally fine. I quite agree that flamestrike is weak. Hopefully they'll review
our aoe spells (but i'm not holding my breath). Also I'm stealing the
flamestrike precast on Norushen, nice idea