Help Designing Epic Levels

[Mada]

I'm running a game set in Ancient Rome and the whole idea of the campaign came from the idea of challenging the Ancient Roman/Greek Deities at the end of the campaign.

For this I want the players to step beyond level 20, something I've seen homebrewed a bit so far. I want to write this up myself, I've seen one system posted here already but it wasn't quite for me.

I'm not sure if I want to take a "write every class to level 30" approach or make a few "epic classes" or just have a general one track thing that people can do from level 21-30.

Input would be appreciated.

[Unoriginal]

Do you have anything against the "give them one HD and one Boon per level above 20" approach?

[Mada]

Not exactly, but I was hoping the Boons would be the rewards they get for besting the Deities once they get to them.

[Unoriginal]

One doesn't stop the other. You could also have "defeating a deity" as a condition to level up after lvl 20.