Oooo, on a related topic, I'm making a group of NPCs who will be the next BBEG group that my party will face. They're based around the idea of "infinite disposable minions", because we all know that any problem can be solved by sacrificing minions.

They're each CR 15, but the PCs won't have to fight them directly -- these guys got to high level by NOT sticking around for the end of a losing battle.
1: Nomad 5 / Thrallherd 10: "The Wheelman". He has taken Expanded Knowledge twice (for
mindlink and
astral construct). He provides minions, knows battlefield control powers and transportation powers, and stays out of melee range.
2: Ranger 5 / Beastmaster 10: "Range Rover". He stays back with Wheelman and shoots people while his many animal companions engage the party. In a pinch, he whips out his halberd and defends Wheelman.
3: Dragonfire Adept 15: "Aurora Aura". She has cast
endure exposure on the minions, so her breath weapons won't destroy them, but if that's dispelled, she knows they're all disposable. She focuses on battlefield control breath effects. Many of her feats are Draconic Auras, and at 12th level she has taken Double Draconic Aura.
4: Marshal 3 / Fighter 2 / Rogue 2 / Dread Commando 5 / Blackguard 2: "Spike". He's the one guy who's actually in the front row. His saves are good, and he has Evasion.
= OR =
4: Bard 11 / Blackguard 3 / Marshal 1 (with a variant evil Devoted Performer): "Chant". He would be another 2nd rank fighter, probably with a ranseur and armor spikes, and he'd abuse [Divine] area-effect feats like Divine Resistance or Sacred Healing.
If I were using Tome of Battle (which I'm not in my game, not until the Players get a chance to rebuild their PCs using it if they so desire), then I'd probably change things significantly.
The most important piece is The Wheelman, for sure -- everyone else is basically there to augment his minions. His minions probably include a Cleric or two, so it should be assumed that everyone will get a free
bless on the first round of combat.
Cheers, -- N