Now that I created the combined mod I finally had a look at the mod nations, too, and I want to comment on that Nephilim hype:
I don't think that the situation is as bad as Nikolai and some others make it sound. Yes, the Nephilim look scary. They have insane def, they have attacks with a Soul Slay as secondary effect. But that doesn't make them unbeatable. Sure, they are overpowered compared to a normal game, but so are the other nations, too. (Except Mushroom Kingdom. That's only in there for the giggles, I think its power level is about vanilla game) First of all, having seen it happen in games against other powerful nations in base game all the time, diplomacy is a powerful thing. If two or three people ally up against somebody, then usually he has no chance but to eventually lose. They can overpower him by numbers alone and make his economy go haywire, leading to his eventual downfall. Now, about those Nephilim. Yeah, they have insane def, they have powerful weapons, but they're not invulnerable. High Def means that you have to either a) swarm them or b) exhaust them or use other means of attack, like ranged attacks. They do have zero prot, after all, so they are naturally VERY vulnerable to ranged attacks. The Soul Slay effect of their weapons is intimidating, too, but at least you can MR resist it. If a Jotun hits you then usually you just die, too. So you say, they are sacred. They can be abused with an air/earth bless. That's true. But they're still very expensive. Look at their gold price. They're well worth the money, but it's a very limiting factor for them. Their national god is scary, too, funny thing is that he wasn't restricted to that nation so everybody could recruit it before...
I fixed that, of course. And then there is the downside: it's a blood nation with sacrifice dom. Their freespawn never heals. Lots of those other nations have way better freespawn, I think.
So to make it short now, I don't think that the Nephilim are that much out of the league like the hype made it sound. And no matter how powerful the individual units might be, they won't be able to overpower an alliance. So please calm down, have some test games (and not just against indies) and try to design a pretender for your nation for the game, yes?
P.S.: As said before, Mushroom Kingdom is not as powerful as the others, IMHO, I'd say they could be used in a vanilla EA game. Those Seraphim that I added are what Amos considers the "most balanced nation" of his creations, too.