Is Conflux a broken castle?

Conflux is a strong castle, but not overpowered. Fairies die instantly. Encountering Fairies is a Necromancer's dream. Strong, unupgraded units of levels 2-3 – how else? Fire/energy elementals – an average unit considering everything. Earth elementals – that's just laughable. Psycho/magical units – the damage is area-of-effect, but they only have 75/80 health and low damage. Birds and Phoenixes – well, you have to compensate for the drawbacks somehow. In general, the castle is very dependent on upgrades, even though they are cheap. But they take resources and time. University – and you don't want to pay the money? It's not overpowered in any way.