Well, Nagas dominate there and are very powerful; I wouldn't refuse them, but I still prefer Djinns in the old-fashioned way. They seem to have more initiative, and you don't often fight against just Black Dragons or Berserkers. In principle, I agree that making the 2nd and 3rd tiers magical isn't very sensible, but IMHO, it fits the concept of the castle and is quite powerful.
🏹🎪+⛓️♿=💕