My original 3.0 campaign with my two sons ended up with my oldest son declaring he wanted to permanently slay Orcus on his home plane. That became the overarching goal of the entire second half of the campaign. They took a lot of steps to significantly weaken Orcus so slaying him would actually be feasible and in the end my oldest son's cleric PC did in fact kill Orcus. But he did it by betraying my younger son's sorcerer PC, backstabbing her through the heart with his fiendslayer longspear so her inherent goodness could be channeled through the spear to slay the Demon Lord, since the spear's head stabbed into Orcus immediately after piercing the sorcerer from behind, linking the two of them. Unfortunately, while it did slay Orcus, there was enough "backwash" to instantly corrupt the betrayed sorcerer and she took over as the new Demon Princess of the Undead, gaining all of Orcus's power in the transition. You can probably guess her first action in her new role; things didn't work out too well for the cleric PC after that....
Johnathan
