Unique bosses are really a plus to any rpg map,
The bosses are boring when you just need to attack, attack and attack them, this will result in defiances rpg, the bosses are killed with only hackslash, attack, attack and attackk!!A cool rpg must have unique bosses, that you have to do something,Example: like a huge Abomination in a laboratory with a mad gnome scientist, if the abomination is immune to attacks, you have to purge it by activating a lever that is hidden and guarded by enemyes, than it will be vulnerable for some seconds, than smash it down as long as you can, it will be up again when the purge wears off, than you must do something to make it vulnerable again and blablçabla than fight the gnome and his contraptions, another Example : a necromancer in a graveyard that keeps raising the dead to kill you, than when you try to attack him, he in a few seconds become a ghost invulnerable to melee, than you have to cast spells to continue dealing damage, he summons another dead dudes but then you remember that in the graveyard there is the tomb of a Paladin that still has power, wich damages undead that come near it with light or something similar
THIS would do a cool rpg, where u need skills and inteligence, not a hero with lotsa attack and stats and a boss that you need only to buff yourself and then press A on the ground and wait....