Shortcuts for GMs preparing a boss sheet

Question

Due to time constraints, I simply do not have the time any more to read through the list of all the feats, all possible enchantments, and all the prestige classes, to then build a boss.

What are the shortcuts for a GM to avoid spending 2 hrs each time to create (in my case, "epic") villain NPCs for each boss fight?

The manuals' suggested NPCs are dramatically inferior to the PCs in our campaign, in spite being of the same level as the PCs, from the perspective of feats to the spells known; so I have never taken them into consideration.

We don't use any ambientation's manual (e.g. Faerun) nor Tome of Battle or Tome of Magic.

Answer 1

As a single father and multi-campaign DM, I use and re-flavor published monsters of the appropriate CR-- for you, 20 or higher. Perhaps borrow items from other creatures, such as health regeneration from vampires, etc.

Also, it sounds like your boss fights are against a single enemy. Instead of spending all of this time manually building out an NPC as if they were a PC, grab one from the Monster Manual and invest your time in making a challenging battlefield-- traps, harmful terrain, obstacles, forces of nature that work against the characters such as the ground shaking every round, forcing saves to stay standing-- and minions that surround the characters and force them to divide their attention away from the main boss.

Answer 2

I've had generally good experiences through cheating.

Let me explain...

Most NPCs won't last past the first few rounds of combat. It's staggeringly unlikely that a 30th level wizard's chosen cantrips are relevant, or really even what 7th level spells they have prepared.

So, don't choose them.

Or, at least, don't pick them all. Select the top 2 levels of spells as normal, and pick a couple of utility or back-up spells they have at lower level. Sure, the party might find the wizard's spellbook and want to know what's in it, but that's what random tables are for (just be sure to include the spells you chose for them). The spellbook randomly has wish but the wizard didn't use it? No worries: they must have already used it today, or were short of the material components, or even 30th level wizards with triple-digit INT scores make bad decisions now and then.

Similarly with gear: pick a couple of unique things they have, and ballpark the rest. Or, build a couple of default loadouts that work well, generally (Cloak of Resistance +5, Item of <Key Ability> +6, Ring of Evasion) and just customize the last few thousand GP of stuff.

Feats fall somewhere between the two. There are some good go-to combos (summoner wizard? Spell Focus (Conjuration) and Augment Summoning probably go in there somewhere; evoker? Spell Penetration and Greater probably belong), which should leave enough room for one or two interesting feat choices that make the wizard feel sufficiently different from the wizard the party met last week.

It's a little harder to cheat with pure-martial characters, but my experience is that they're often easier enough to build (especially with a good gear bundle) that the actual build time is about the same as a cheat-ed wizard.

As Ned's answer suggested: re-skin things. Also, add templates or just racial hit dice. And, creating interesting encounter areas is a great idea! An encounter in a giant clockwork, where the characters need to be aware of which gears are safe to be on this turn, can help transform "yet another golem" into an adventure to remember.

The last question in this Angry GM (content warning: lots of grawlix swearing and snark) mailbag post (scroll down to "Dino asks") talks (indirectly) about pulling 4e and 5e mechanics into other systems. Both have some variant of recharge abilities (3.5's got a couple, but they're bespoke - a dragon's breath weapon is the best example off the top of my head) and lair actions. The former are pretty simple: roll a d6; if it rolls above an X (where X is largely determined by how powerful the effect is), the ability's ready again. Lair actions are a bit more foreign to 3.5: basically, a creature in its place of power (a dragon in its cave, a lich in its tower, etc.) can tell the lair to do stuff - drop stalactites, hurl books, try to banish intruders, etc.. Granted, this may feel like it's getting away from "follow[ing] the same rules as for the PCs", but ... meh. NPCs will always be outshone by the PCs (right up until the TPK), and are on-screen a lot less than the PCs; let the NPCs get away with a few things here and there that the PCs might not be able to (or, at least, might not be able to easily). Maybe the dragon didn't actually use a "Lair Action" to cause the stalactites to fall; maybe it knows the resonant frequency of its cave and, through decades of experimentation and practice, can growl just right to cause minor tremors...

I would add to that looking at Pathfinder's Mythic system. Just slapping mythic tiers onto NPCs probably isn't the best path, but pulling in a couple of those abilities to juice up a boss that looks a bit dull might be just what the cleric ordered.