I still believe that any castle can be defeated by any other. And there's a way to counter the Conflux! Everyone is strangely silent about such a wonderful castle as Inferno! It's an excellent castle! Efreet are awesome! I've liked this castle for a long time, and I still enjoy playing with it sometimes.
If you list the castles in order of preference, you get:
1. Necropolis
2. Inferno
3. Dungeon
4. Tower
5. Conflux
6-8. Haven
6-8. Fortress
6-8. Rampart
9. Swamp