[quote=@Dead Cruiser]
Ehhn, I can switch my idea entirely if you'd prefer. Having two water/chaos/life-themed characters would be a bit much, I think, even if one is using Tiamat and the other is not.
[/quote]

No, it's quite alright. There are plenty of mythological figures that are similar to each other, so thematic redundancy isn't something I care about at all.

[quote=@Dead Cruiser]
And just for the record, I was not planning on using a being from Lovecraft's mythos. I was going for a Lovecraft-[u]inspired[/u] character. Specifically, he was partway mutating into a Chaos Spawn, and as such was beginning to take on characteristics of some kind of fishlike monster, not unlike a Deep One.
[/quote]

...this is why I was thinking of putting all the rules of magic into a separate document. A "Chaos Spawn" is a classification of spirits used in [i]another[/i] setting of mine, not the one for this game. In this one, spirits are just spirits. Some of them were spawned from fragments of the Primordial Chaos, and thus have chaos-themed powers. You don't exactly need to mutate to be a fish-like monster, as there are already plenty of fish-like monstrous spirits around.

[quote=@Dead Cruiser]
I might opt for a vampire-themed character. For his spirit, I'd like to use a more abstract sort of entity (let's call it "the Dragon" for now), which is an amalgamation of various vampiric entities that have gradually subsumed each other (Cain, Dracula, etc).
[/quote]

Sorry, I don't want to let you hog all the vampiric mythological figures, since other players might want to use one of those. If you want to play as a vampire, you'd have to pick only one of those vampiric figures, e.g. Dracula, Orlok, Carmilla. Additionally, Cain is a member of the uppermost echelons of the Infernal Legion, so there'll be some more caveats if you want to play as him.