With all of the devilish delights you'll find in Fiendish CodexI I: Tyrants of the Nine Hells, you'll have plenty of material to work into your campaign. However, you may not want to introduce your players to higher Challenge Rating archdevil aspects right away. Instead, use one of the aspects you'll find in our series of web enhancements.
The concept of archdevil aspects was first introduced in the Miniatures Handbook. The aspects presented in Chapter 5 of the fiendish Codex II are significantly more powerful and are intended to serve as adversaries for climactic encounters at the end of a standard D&D campaign. These aspects incorporate a much more significant portion of an archdevil's life force, to such an extent that an archdevil can have only one such aspect in existence at one time. The following web enhancement provides aspects at a lower Challenge Rating, for campaigns in need of worthy, but less powerful, adversaries.
What is an Aspect?
(Adapted from the D&D Miniatures Handbook)An aspect is the embodiment of a small portion of an archfiend's life force. The original's power is so great that this shred of life force is actually able to take shape as a living creature. An aspect looks like the archfiend from which it springs (known as the aspect's "original"). It is only a pale shadow of the original archfiend or deity. Still, a pale shadow of such a mighty being is formidable indeed.
While aspects are spiritual rather than biological in origin, they manifest as actual living (or undead) creatures. They have consciousness, intelligence, and will. They are notoriously single-minded and unwilling to communicate. They may help mortals, but only because they want to--not because they're asked. Aspects are usually as big as giants, although they are sometimes scaled more like humans. It is very rare for them to be larger than Large or smaller than Medium. In the case of archfiends, aspects are the same size as or smaller than the original.
Unlike avatars (introduced in Deities and Demigods), aspects are not extensions of the original. The original can't see through the aspect's eyes and doesn't know what the aspect learns. Destroying an aspect sometimes weakens the original by dissipating the aspect's life force and preventing it from being reabsorbed into the original, but beyond that, hurting the aspect does not harm the original.
Characters can sometimes use the planar ally or planar binding spell to call an aspect. In the case of the more powerful aspects, greater planar ally or greater planar binding is necessary.
An aspect is an archfiend's power coalesced into a single point. Typically, this power can't coalesce into two nearby points. Thus, aspects of a specific original are almost always found alone. Sometimes spellcasters or creatures wielding powerful magic items can force two aspects of the same original into the same area. These aspects are likely to attack each other. The proximity of another aspect of the same deity apparently causes an aspect great distress.
Vile servants of archfiends and evil deities sometimes call forth aspects of their unholy masters to take part in unspeakable rituals. The less said about these rites, the better.