I believe that the fighting should work in a way similar to the game Heroes. Where markers will show up showing where a boss will attack, and those attacks are the main damage dealers. Another damage dealer will be that when you move in to attack, say thorns will come out of the enemy, which deal light damage to the player. This would be in place to prevent players too low level from killing the boss.
Bosses should allow you to go to a new world once you do a certain percent of damage, and the boss is defeated, so that you can’t be carried to the end by a much higher level player. Bosses should drop interesting weapons that have special abilities built into them, say something like Meta Knight’s Blade.
I’m interested to hear what you think, and I bet the devs are too, because based on the feed, you can tell they listen! Stay great!