When they roll out multiple droid dice, use the first with the highest value for focus then turn everything else to damage sides.

If you can remove one of the seeker droid dice, not only does it stop the effect of that die, it also lowers the power of the other seeker droid dice. So target one of them with a removal effect. Or you can have a big removal spell like Block, or Force Misdirection ready for after they focus. And probably most importantly, target the Seventh Sister first, try and take her out before the droids get too strong.

Lots of things have a value of 3. The key if you are having problems with them is to kill the Sister before she gets 3 of the droids.

I'm having a lot of fun and luck with 1 die Seventh Sister, 2 die Director Krennic. I know it's not top tier but it's still taking on the big dog's with consistently.

kill the character with the seeker droids or the SS

another fun thing to do, provided the opponent doesn't have force speed special, is hold onto any "wide" dice mitigation like sound the alarm or defensive position etc. to make your opponent really, really mad

There are a few cards that remove all dice with a value of two or more or that display a certain symbol. They pretty much end a turn if your opponent plays as expected to maximize his damage.

If your opponent does nothing to counter this losing a turn is a problem.