Good thread, some day the PCs in my game will have to slaughter the gods, and I'm terrified thinking about how I can run that...
I wanted to ask, though. Are they going straight for Vecna, or have they been "weakening" him? I mean, taking out his champions, anyone he might have loaned a divine rank to, razing his temples, etc..? The rules probably don't have stipulations for such things weakening a god, but I'd think it would help. In my case, I want the PCs (gestalt) to start deicide by level 20 if not earlier. I'm already going to have to lower the power of the gods for that to even be remotely feasible. But I thought I could at least structure adventures around doing those kinds of things first, to set up a god for destruction (and give a mechanical justification for why the hell they can be killed by the PCs).
Also, what are the rules for what happens to a god's divine rank when he's slain? Do the slayers just get it? Does it dissipate (you can only "earn" divine ranks over time or whatever)? I figured the party's deity would have most of the power go to him, and I'd eventually reward them with rank 0, to become demi-gods.
EDIT: As far as AMF goes, just use the level 6 version, not some epic version. Thus, all of Vecna's spell work in it, but the wizard, who should have
some epic spells by now can still do something. He just won't have many spells he can use. Really, not much different than level 1.
Of course, I don't consider epic spells to be "mortal magic." Maybe that goes against RAW.
The other option would be a Warblade or Fighter with some Martial Study feats punching through the AMF with Iron Heart Surge.