Yes make him a bit harder on NM (again, i cant say anything about the other difficulties, does it scale down automatically? or is it a setting for each difficulty? i really have no idea ;) )
This may be a long shot here, especially since the contest is at its end within a week but it would be REALLY cool for the boss to have some sort of mechanic. I know I'm probably asking a lot here, that is because i have literally no experience with the dddk (i did the initial guide but that's about it).
For example: Boss spawns four minions at different locations (maybe the corners) each giving him a immunity to a specific form of damage, so at start he'll be 100% immune. Now, if you want to fight him with physical damage you need to take down the minions that protects him from getting physical damage, same for the other minions, electric minions, fire minion and poison minion. If you only take down the physical minion you can beat him with physical damage but he still is immune to the rest of the damage and absorbs 75% of the physical damage you deal.... You get the idea where this is going.
But hey, I really think that is not as important as getting some of that other stuff fixed, just if you have time and the knowledge
thats sounds very interesting, will check if I can set something like that :)
there are some bad news about adding sharken and djinn enemies, I think we cant add enemies from the dd updates, looks like these classes still dont appear on the DDDK.