I’m no expert at raiding, but my enjoyment with this part of the game changed dramatically once I learned a few things about special attacks:
The more you hit a target, the faster they strike you back with their special. You therefore want to kill them before they do so.
How do you do that? You kill the guy in the middle first.
This wasn’t obvious to me, but when you see the defense target team, you can then edit your team.
Kashrek? No problem, bring three red heroes and match the red tiles until he’s dead.
Three red heroes makes your red tiles hit three times harder. Of course, your other colors will hit for 1, but you just avoid matching those colors.
Ok, so you killed kashrek, but now you have to kill their blue heroes with the red tiles. You keep passing tiles through the gap in the center. This will help you charge up your heroes without giving the defenders mana. Now just fire your special attacks at the other heroes and use your strong color to good advantage.