Have you ever made your characters face Anti-PC's?

[tetsujin28]

And remember: Overly powerful magic items can be destroyed, stolen, depowered, powered down, reclaimed by their rightful owners, reclaimed by someone other than their rightful owners, made unusable by the characters, made unwise to use by the characters, etc.

Sunder, sunder, and more sunder

 

[Oberyn]

their magic items arent really what make them so powerfull. At the moment i am going to nudge them into spending some of that gold on a kingdom.

 

[Keeper of Secrets]

Whereas I have never done the 'mirror image' villains, I did pull a stunt once where the characters had their bodies switched with villains and they had to actually fight their own characters (who were posssessed by bad guys). That went over rather well.

 

[Silver Moon]

On our world we have the ultimate anti-pc, namely an alternative-world version of one of the main characters. Both are now reasonably high-level druids, but the anti-version has gotten involved with the group's top enemies. The character and her counterpart had a duel in a module a few years back and I managed to sucessfully have the anti-one escape, so it continues. It's cliche, I but I love the "evil twin" plot device.

 

[Luthien Greyspear]

I once tossed a band of "supercops" at my party, specifically to exploit the lack of tactics in the party. The party had run afoul of some local laws in Wintershiven, which is a theocracy. Specifically, they were accused of "graverobbing" (really, they were fighting evil necromancers, but the cops were ignoring such niceties as details). So, the Church Militant sends a posse consisting of a couple of clerics, a couple of fighters (no paladins, 'cause I wanted a fight), mage, bard, and 'investigator' (rogue). They track the party to some caverns, and wait for them to rest. Ambush in the dark, and all fall down.

Basically, the Church Militant used spells which enhanced the cooperation of the group, while the party had an 'every-man-for-himself' attitude in combat. Since this was 2e, the CM was casting a lot of spells from the Law sphere, like Defensive Harmony and Strength of One, giving everyone a 5 point boost to AC and a strength of 18/96. The last one to go down in the party was the mage, because he was avoiding melee combat. Fortunately for the PC's, the CM was only interested in capture, not execution.

Of course, both groups got ambushed by a troglodyte tribe and tied to stakes in a subterranean buffet line, but...

 

[Aeric]

I've run a lot of games that didn't last long enough for the PCs to meet their nemeses, but I always designed them ahead of time.

Something I've always wanted to do is have the PCs fight evil clones of themselves.

Hopefully my current campaign will last long enough for me to do both!