Rewarding Creative Players and going too far

[WhoAmI?]

Ok playgrounders, with the recent trend of time travel threads on here my DM decided to include a segment where the players travel back in time about 2000 years. Since this is an evil campaign, one of the players is a chain devil, and he managed to put together a plan that, over those 2000 years, would collect him a huge amount of souls (like, several tens of thousands), and my DM decided to let him consume each of those souls for 10xp each (the book of vile darkness says souls are worth 10xp each), immediately shooting him up into epic levels and archdevil-ship. There's a story mechanic that stops him from operating on the material plane with that power however, so what he's done is made an aspect of himself at the same level as the party and uses that to travel around with the party, while his main form deals with politics and realm management on the nine hells. The storyline is such that the players all actively work together, there's some group disharmony, but mostly we all get along, since the goal is to save the world. So at least until the end of the campaign, we aren't gonna go for eachother's throats.

My question to you playgrounders is this: Is it ok for a DM to reward creativity in this manner? Or is allowing one player to gain epic levels (even if it's just in the shadows so to speak) going too far? Since the main form can use it's power to benefit the party on a whole, does that make it ok? Or does it sound like playing favourites?

I'm personally cool with it, I think it's a decent reward for such creative thinking on how to utilise 2000 years to collect souls, and since all the power gained is technically inaccessible to the player it doesn't make a huge disparity between the party, just gives the player a sense of satisfaction of having achieved something great.

[originalginger]

If mechanically it makes little difference to the play, and is mostly flavor, which is what I understand it to be from your description, then I say just roll with it. If it gives that player some marked advantage over the others, negatively impacts game balance, or somehow detrimentally affects anyone's fun at the table, then it should be addressed and dealt with to everyone's satisfaction.

From a DM's perspective, I am not sure I would rule in favor of such a thing, but I don't know your players, the dynamic at the table, or the ins and outs of how it affects the game as a whole.

If it needs to be addressed -
Has The Book of Vile Darkness been regularly used in the campaign, or did the player pull it out specifically to perform this plan? If this is the book's first appearance in the setting, the DM could rule that the book doesn't apply in the setting and shoot the whole plan down with little room for argument. Even if the book is considered fair to play from, the DM could house rule that souls are only worth 1xp to time travelers, nix the rule altogether, or otherwise use fiat to deal with it.

Edit because I am a terrible typist, especially at 3:30 am.

[ArcturusV]

I... probably wouldn't have done that myself. Mostly because such a rapid ascension (2000 years to a devil is typically nothing) in power would generally bring the other devils together to put the upstart in his place. He'd need some masterful political maneuvering in the Nine Hells to keep from everyone just tearing him down before he reached such a level he was a real threat.

As such I'd probably keep his Arch-Devil status so focused on maintaining his own position in hell that he cannot really reach out and help the party. Boons need to be focused on doing something that directly protects his position. Because his ass is gonna be under siege. Not just from the forces of Good who are probably gunning for him, but Demons and Devils too.

Thus his "Aspect" that he uses to adventure with you is more of a last ditch effort to secure his position. If he can score such a coup with this part of himself, and have enough power gained to roll it into his main body, he might secure his status as an Arch-Devil. As is, you might occasionally find cultists dedicated to him, which may or may not help you if they recognize the "Avatar of _____" walking among you. But it will probably draw too much attention from the Arch-Devil's enemies to be constantly relied upon.

That's probably how I'd play it out.