Tactics class. Begin now.

[pppo]

The heroes get most of their power from their magic equipment and spells/abilities. If the evil guys use an antimagic field kidnapping the heroes will be much easier.
It will prevent the enemies to use magic themselves, but therefore mundane methods like poison work much better on heroes with low saves.
If the enemies use psionic powers it becomes really nasty.

 

[Enceladus]

If you can split them up... Ogre turned into a ghoul with monk character levels.

He will fail a save... soon.

You scare me!

 

[MarauderX]

I don't think anyone mentioned this...

Use Wall of Whatever (Ice, Fire, Iron, Stone, etc.) to separate the kidnap target from the party, then throw some simple web spells (like 4 at a time) at him to keep him still. Then use a high Reflex save NPC to tumble in and disarm him, or launch some charm or sleep spells at him until he fails his save. Or you could have some high strength baddies rip him out of the webs, grappling, and take him back to base tied up.

 

[takyris]

Spellcasters, you say?

I've always enjoyed the delicious creamy goodness of:

Greasing the area under the characters' feet

Throwing a net on them to keep them still for a bit, combined with the Grease

Having the party tank wander in. His armor has Silence cast on it, meaning that the characters, netted and slipping on Grease, are also effectively Silenced unless they have SR. Tank begins whomping.

The evil wizard, who has Spell Immunity:Silence, begins unloading Enervation spells on the netted, Greased victims. The evil cleric, also SI:Silence, alternates between whomping (assuming that he's got a good attack bonus) and casting take-out spells like Hold Person or Bestow Curse. He casts spells on people who have negative levels, of course.

When one or two people are out of the fight, the party tank attacks via grappling, and the party rogue, who threw the nets, wanders in with his sap to attack grappled targets (who are vulnerable to sneak attacks).

Needed: One tank (two if you can spare it), one cleric capable of casting two fourth-level spells, one wizard capable of casting two or three fourth-level spells, and a rogue (or someone else with exotic weapon proficiency in net and sap -- the rogue gets the sap for free, but would purchase the net proficiency normally). A party of 8th level characters -- or 9th level casters and 6th level warriors -- could take out an odinary group pretty easily.