e stands for Epic. Essentially, characters don't add levels after this level, instead gaining additional feats every 5000xp they earn for e6, and maybe 1million xp for e20 (haven't run the numbers yet, but I'll count encounters for 20th and compare for 6th how many it takes to get an appropriate/equivalent xp pile). This is based on a houserule set developed here
on the boards. I believe it was inspired by a certain article
; or that they came to the same general conclusions: 6th level is epic for most fantasy concepts and most challenges (ie: walls to jump, locks to pick, skill check DCs to be reached).
e20 is what I'm using for my new pbp, where I learn the hard way what high level play feels like; when we beat creatures I homebrew, I'll post them here!
The creation guidelines I'll be using are straightforward. Monsters can generally be whatever I want, but I'll try to build concepts using templates as often as I can. For example I have a Balrog of Moria made for the e6 game that's, well, nigh unbeatable by a party of 6th level heroes... although if someone can figure out a reasonable attack plan, I'm all ears. It's not high level, however, but it is CR9 after all the templates are added up.
For e6: PCs and Monsters will typically use Max hp, excepting minion-style mobs, who I'll leave at half hp (standard Bestiary hp). e20 I have no idea what I'll do, until after the first combat with my new group.
Monsters can come from the Bestiary(ies), but I'm adding templates from the Advanced Bestiary from Green Ronin, and potentially WOTC templates I like a lot.
Monsters of Legend: the rule for my e6 Homebrew is that all the treasures in the core book are in the setting *somewhere*, including scrolls of ancient spells, rings of wishes, the Holy Avenger, etc. Not only that, but they're in specific places on the map that will not change as the PCs advance, meaning I've designed the encounter locations and they will stay that way (or wil when I do them): there is one vault beneath lake X that hold the ring of three wishes, with particular challenges associated with getting it.
If the PCs can get the item locations, they can keep them. HOWEVER the more powerful the object, the less regard for CR I'll have when designing the encounter. For example, there is an Ancient Red Wyrm in the setting, guarding a hoard of treasure whose gp count alone is worth millions, let alone the arsenal of +5 magical items and other treasures lying about; the catch being that, to get them, you need to contrive to survive and loot an Ancient Red Wyrm with an arsenal of +5 magical items and other treasures at its disposal. Still, this and other such monstrosities exist to challenge heroes and make the setting feel real. Also they'll have to be found, and there's the joy of knowing a suitable compensation for victory is included.
The Crawling Chaos is one such beastie, who was guarding a djinn noble (who could grant a single wish); however, the treasure hoard they got was due to them not having *any* magic on them and surviving this sucker, albeit by freeing said djinn and ending the encounter. They used their wish to trap the beast, as they didn't have the area effect magic to defeat it (swarms, btw, are nasty in e6; read the stats!).
I don't know how this will play out for the e20 campaign, as 20th level characters can usually handle anything. I may just throw avatars at them and see if anything sticks. They don't need items except for plot reasons (ie: the key to dimension X or portal Y, etc.