The wizard in my epic campaign have grown very fond of Otto's Irresistable Dance, simply because there isn't any save against it.
Picture this: The PCs want to get their hands on a particular artifact, guarded by a chaotic evil dragon they know to be way over their level (they were at level 23-26, the dragon was CR 34!). They find the dragon, try to bargain with it, try to sweettalk it, the dragon tires of their nagging and decides to eat them.
During the first round of combat, the wizard and cleric go first on initiative, burn off two spells each (3.0 haste :\ ) They roll 18s and 19s on their checks to beat his CR, yet the dragon is unaffected. The three melee guys close in, but the dragon actually has a decent DEX and Combat Reflexes, so he gets an AoO against each of them, taking roughly 1/3 of their HP. Then it's finally the dragons turn...
He tries to snatch the three melee guys with his claws and teeth, but the PCs had planned for this so they all had Freedom of Movement on them. They still loose another 1/3 of their HP, though, or in the case of one guy another 2/3!

(That was the party's rogue, I think he had something like 3 HP left.)
I figured the PCs would have learnt their lesson now and would start round 2 by planeshifting out, but the wizard surprised me: He cast Wish, wishing that his next spell would beat the dragons SR. I gave him a +20 on his next SR check and he pulled out his metamagic rod with maximize spell. He then cast an empowered, maximized Otto's Irresistable Dance.
For seven rounds, the dragon could do nothing but boogie while the PCs pounded at it and finally dropped it on the very last PC action before the spell ended and the dragon could attack again...
Yep, they all went up a level that night!
