Great game all round, but there are so many things that can be done!
First, I would like you to add a "dungeon defense" mode where you can put down defenses, minions and your other bosses, you would be able to switch between bosses at will, when your throne is destroyed, game over and you get rewards according to your time survived.
Second, minions should be better, allow us to equip minions with their own gear, make it so your troops can spawn in different presets (starting with 3 or 4), also, let us decide to bring 1 of our own bosses or a personalized minion bodyguard regiment instead of a random other boss on the internet.
Third, more classes and differences between races, (such as racial skill lines), orcs, minotaurs and dark elves oh my! So much fantasy material to go with to be the perfect boss. There should be a "dark priest" type of class, or a evil shaman or a sort of barbarian type class. Racial skill lines are a must, right now race is only a cosmetic choice, but a skeleton should have different skills then a dragon.
That's it, bye.