From the front of the book:
Welcome back to the series of web enhancements that bring you a slew of aspects that you can use in your game. In this final installment you'll find a collection of unusual and seldom seen demon princes, including an aspect of the Mother of Demons. Now you have aspects for almost every demon prince published in Fiendish Codex I, and you can use any of them to challenge mid-level adventurers. Remember that if a particular demon prince has more than one mode of operation (melee, spell-like abilities, some strange ability like Fraz-Urb'luu has), you can modify these aspects by changing the feats and/or the special abilities to reflect a different operating mode. For example, Baphomet has breath weapons, but the aspect included in this PDF series does not. If you want an aspect of Baphomet at the same challenge rating with breath weapons, then change the feats to less combat-intensive ones (from Baphomet's list) and replace Powerful Charge with one of Baphomet's breath weapons. There are a lot of possibilities with the aspects, and you should make them what you need for your campaign. As before, each aspect has entries with suggestions on how to use the aspect in the EBERRON® and FORGOTTEN REALMS® settings.