Yeah, it's crazy-stupid-hard to learn how to start playing a 21st lvl PC from scratch. Imruphel has a cool idea about playing different combats at different levels. Frame them as flashbacks, and make them plot-rrelevant against the minions of a repeating foe.
For the DM:
- It's a little more work, but advancing a "traditional" monster is often much cooler than pulling out a shiny new monster that no one has heard of. When doing so, you should often ignore the "max HD" listings if you'd have more fun not being limited. A 40 hit die carrion crawler lumbering across the landscape is a thing of beauty.
- You'll want a reason why these horribly powerful monsters and foes haven't conquered the world. Otherwise, suspension of disbelief can get a bit strained. At the least, give suitable powerful foes a cool back story.
- The PCs will be immune to all sorts of things (for instance,
heroes feast makes them immune to poison for 12 hours, something my gargantuan scorpions and I recently found out the hard way.) Run with it. Nerfing PC abilities more than occasionally isn't a good idea.
- Let them feel powerful. Occasionally throw a hundred humanoids at them, just so their area effect spells get a good workout.
- A recent Dungeon had an EXCELLENT article from Monte Cook on guesstimating high lvl stats on the fly. It's a must-read, and will save you many hours of prep.
- When building high lvl NPCs, quit fretting about where every skill point, every spell and every feat go. Most won't come into play, so only determine the important ones.
- A cool power that is never used is no cool power at all. Find out what the PCs are immune to, and make sure they get attacked with those energy types. They'll be thrilled... at least, the ones who prepped will be! Likewise, plan challenging adventures that let the party shine. If you attack with rogues, the epic rogue in the party will be thrilled that no one can sneak attack him. That sort of thing.
- Bigger, or more, is not normally better. I wouldn't have used the beholder encounter you led with unless I could rationalize why so many beholders would be in one place. As a DM, try using clever tactics instead of tougher/more monsters to make combats more interesting.
- Understand probabilities. The beholder fight was difficult because when lots of eyebeams are flying, the chance of rolling a "1" continues to rise. This is also true with massive damage saves.
- The effectiveness of an epic party varies substantially by whether or not they've had three rounds to buff. An unbuffed, unprepared party is MUCH less effective in combat than one which is expecting the foe.
- The traditional dungeon is mostly a thing of the past when you can wind walk and ethereal jaunt. Use some anyways, but don't be sad when they're easily circumvented (doing so is fun for players.)
- Design adventures that challenge the players, as well as their heroes. Political games are good at this. Feel free to design mysteries that can ONLY be solved through the use of high lvl divination spells.
- Make battlegrounds with cool, interesting features in them. They'll make combat more fun, and give epic adventurers tools to use during a fight. (Example: an epic rogue jumping from platform to platform over lava, an epic wizard telekinetically tossing around huge jagged boulders.)
I'm sure there's more things, but that's a good start.
)) and go back to your players and, if you are still insisting on starting them "cold" at 21st level, run them through some mock combats with the same characters but at, say, 6th, 12th and 18th levels. Let them get to understand how the different characters blend their strengths together as a team. Ideally, make those mock combats part of the campaign backstory.
