The game is 3.5, the group is level 10/11. Ranger Druid, Paladin of Freedom, Barbarian/Sorcerer/Dragon Disciple, Cleric/Adept, Bard
Books: PHB, DMG, MM I through maybe MM III. Maybe a bit out of Complete Adventurer.
I'm planning an adventure that might run into a fiendish plane, a nightmare...