Yes I hate it, i've lost to the same. Firstly you need to know early enough he has 2 temples and that he's going casters.
- I haven't tried it but I will if they do it - massing breakers. They can't posses them, so you can retrain blizzard with the AM and lay down the shit on the banshees while breakers there attack the fiends and banshees. You can also use some morts with that. I have to try it.
- Use only griffs and kill firstly fiends, then bashees. They can't posses them. Watch top replays, you will see that it's all how you play the game - just because he has fiends doesn't mean you shouldn't use griffs. The rest is micro and strategy. HU goes griff when there r banshees, in the past I would go knights, they posses 4 knights then it turns the game, so wrong.