[Red Mage Black]

So, someone on myth-weavers is running a custom solo game for me. They promise it's going to be awesome. The starting background is styled after the fertile crescent with pseudo-Ancient Greek architecture and crystal spires created by magi. The story is probably going to start off standard high fantasy and probably dip off into horror territory. They mention it something like Madoka Magica style tragedy.

Fluff behind us, my DM and I need help coming up with a customized template for the descendant of a Concordant Killer(MM4). Problems I've been having is how to work it with this game and how to plasuibly hold on to it for the future. I've been told its better off being made into an evolving template. I'm not sure what this entails, but I assume some folks here might.

I've been thinking of meshing half-celestial and half-fiend together, but should it be more like aasimar and tiefling? I consider the former more because they are the direct descendant/first generation of such a bloodline.

The DM wants to start with no alignment, not N, just none at all. It'll affect appearance(think like Fable but more extreme) and possibly abilities concerning the template.

Someone suggested Nephilim for a name, but that's irrelevant. I just thought it sounded cool. Problem is, what should the abilities be? Ability scores? If the template won't carry an LA for this game, what would be a good template mix? +3 is the highest in that regard. For future reference for other games, what should the LA be?

I ask here because the DM has been busy building the setting and story.