XP or no XP, if the group surrounding the captive is just a boss, it will spawn multiple bosses, which makes your unique boss not unique, and is too difficult for some ATs. If you create a custom group, there is a good chance bosses, and even lieutenants won't spawn if the player is set to a low difficulty, and if you make your "unique" guy a minion or lieutenant players set to a high difficulty will get multiples.
So no, there is currently no way to do what you want.
Eva Destruction AR/Fire/Munitions Blaster
Darkfire Avenger DM/SD/Body Scrapper
Arc ID#161629 Freaks, Geeks, and Men in Black
Arc ID#431270 Until the End of the World
Can this be done?
Lets hypotheticaly say I am writing an X-files arch (it really is hypothetical). Lets also say that in one of my missions, agent Molder is kidnaped by the Smoking man. The objective is to free Molder FROM the smoking man. Can this be done and if so how? The story I am working on has SEVERAL Defeat such and such to Free/rescue Idiot that got captured. So far the only way I can find to do this is to create a custom group to surround the captive but then for anyone to gain xp for doing it, there have to be all 4 of the types in the group and you never know what is going to spawn in the group. Also, in some cases there are more than one named boss that need to be defeated to capture the captive (ie Save cinderella from her 3 evil step sisters).
thanks in advance.