Mephistopheles

Being
Affiliation: Nine Hells

Mephistopheles is one of the most powerful beings in the Nine Hells of Baator, perhaps second only to Asmodeus himself. He's personally an arcanist of mythic-level knowledge and skills. Furthermore, he has strong control over a vast organization dedicated to magical research and development. For all the diversity of spells and magic items in the multiverse, there are probably very few techniques or secrets that elude Mephistopheles' investigations. If he hasn't found and mastered something, then he's almost certainly already looking for it.

Mephistopheles' home is Cania, the 8th layer of the Hells. The endless frozen wasteland is peppered with heavily-guarded and -warded fortresses. These hold laboratories, workshops, and libraries, staffed by the fallen souls of brilliant arcanists and sages. From Cania the Cult of Mephistopheles extends across the multiverse. The Cult embeds anywhere it can, from cities to universities to remote arcane sanctuaries. The cultists and their devil allies are always looking to entice new members with promises of assistance and secrets. They're selective, seeking out the most intelligent and skills. As Mordenkainen's puts it, Mephistopheles "has the lowest quotas but the highest standards."

While in his home on Cania, Mephistopheles is probably unbeatable by anything short of several greater gods working together. If he had sufficient warning and time to prepare, not even that would suffice.

Mephistopheles only has two known, significant weaknesses. First, as a devil he's inextricably part of the infernal hierarchy. He's ostensibly subservient to Asmodeus. The Lord of Baator is a brilliant strategist who wants to rule the multiverse. He holds the leash lightly, knowing that it's best to let Mephistopheles obsess over research. But from time to time, Asmodeus needs Mephistopheles' aid, or at least seems to need to it. Rendering such aid takes Cania's master away from his fixations.

Second, like all devils, Mephistopheles' power ultimately depends on the fallibility of mortals. Whether he wants to learn a secret, study a technique, or obtain a unique magic item, he'll usually get a chance. Sooner or later, it will be in the mind or hands of the right mortal: someone tempted to bargain with Mephistopheles or his agents. He's exquisitely patient. However, there are individuals and organizations that are especially methodical about keeping dangerous things out of the hands of morally-weak owners. So some arcane matters may remain out of Mephistopheles' reach, perhaps forever. No doubt he's working on this problem.