The Taboo magic system was an interesting idea on the surface but I don’t really like the implementation since everything he does is somehow rated as a taboo. If he does something against humanity it’s a taboo because he is a hero inside. If he does something against the demons it’s also a taboo because he is a demon prince. Basically, whatever he does it’s a taboo and he gets stronger regardless. I wish there was some restrictions placed on him by this taboo devil pact.