If you're still having trouble:
Predator
Renewal
Balance Affinity
Typhoon
Incarnation
Brutal Slash
Moment of Clarity/Bloodtalons (I think Bloodtalons is aids, but it's good if used properly)
Also highly recommend lightblood elixer (
http://www.wowhead.com/item=151608/lightblood-elixir). Be sure to use it only once you're inside the scenario.
As well as drums of fury (
http://www.wowhead.com/item=120257/drums-of-fury).
TL;DR - Your feet > Big imps > Fuming imps > Umbral imps > Your feet again > Agatha.
The fight is 100% about add control while keeping dots up on Agatha.
Detailed description:
Start fight by blowing everything and focusing on Agatha.
Try to keep 100% uptime with dots on Agatha.
Use brutal slash and thrash when mobs group up. At your ilvl you should only need 1 brutal slash and 1 thrash to kill small dudes.
Watch your feet.
When big imps spawn, RAKE FIRST, then entangling roots one of them. then focus down the other. Second imp will die before roots wear off on first imp. Kill first imp.
When fuming imps spawn, rake and kite in a circle around whatever target you're fighting.
When she moves, clean up any adds you have out, then go to her.
Other tips:
Typhoon is a great way to interrupt both big imps as well as make them walk back. I really only used entangling roots on the first set and any that were still up when she moved across the room.
If you're comfortable with it, and Agatha does not require immediate attention, you can allow the adds to group up and then cleave them all down with a full stack of brutal slashes.
My biggest issue when I did it was keeping track of the fuming imps (the ones that explode) and making sure I was properly controlling them.
Play with your camera a bit to make sure you've always got a good view of where the next meteor is going to fall.
Stay calm!