Okey, now the map is on naga's hand to improve it's terrain.
So your work is to think about bosses.
Bosses what?
Think about bosses' name,description,model,type(str?int?agi?),spells and finally it's boss fight.
You can have an example on the map development thread. Under "Bosses' Section"
I didn't reveal the boss fight because it makes the game less fun =)
Edit: the boss should be a monster in The Scrouge. If you used some Wow's idea is also okey. Although custom's is better.