I have brought it up before buit not into the open, having a Boss Npc that when its attacks and beaten it is grayed out and cannot be attacked and will come alive after a random duration of time. Have maybe one on every planet i think it would make things more intresting and have it drop good items but make it a hard drop rate, any opinions?

Yes, there have been a couple of conversations about this in the past few months. I think I could just about hack it into working.

Back in the Outwar days it was very popular, makes people sit and wait for the Boss to come back alive and get a chance at getting a good item

I like the idea. We already have bioenergy on normal npcs, so it isn't a huge stretch.