ideas for level 51 npc!!

Hello world!!
I have some ideas for the level 51 NPC , to make more fun this game can be changed the system to get the level 51 through an idea to implement the NPC inside one of DR dungeon supplementing them with various bosses.
When you kill the final boss activates the NPC that will give us the level 51 with a special item like a mythical
for be not so very harder like legion the bosses can be killed in 3 or 4 player.
have fun guys.