Hey all,

i want ideas on how to make players character unconscious or otherwise remove them from action in a near definitive way that doesn't involve death. (examples: Flesh to Stone, old style hand to hand non-lethal beating)

It must be by the rules (no "So you go to sleep? Hmmmkay you don't wake up"), it must not involve death or anything fixed only by wish or miracle or divine intervention, it should involve the use of environmental effects, spells or supernatural abilities but not rare or artifact items or highly improbable combinations of things.

If anyone is interested in the why and how:
Player characters are high level do-gooders that are on a spree of successes and sometimes forget they can fail so i throw something unconventional at them to keep things interesting from time to time. So far i already betrayed them using npcs a couple of times, i have made one boss escape the fight and another time they got the information they where seeking stolen from under their nose. In each one of these occasion they felt bad for failing (partially or totally) their quest and found more drive and determination to proceed in the campaign.
This time they'll get a beating from a powerfull evil outsider that's the boss behind more than half of the things that happened in the campaign and was their boss in another campaign, so it's a mix between a cameo appearance of a known npc and a way to tell the players that they still got a lot of work to do.

Thanks for your ideas.