3 mishnayot! 1 - Conspiring witnesses who plot to impose monetary penalties on their victim. The witnesses can divide the payment that they are then required to pay, but each gets the full total of lashes (with a linguistic connection on the verses of the Torah - according to Abaye, vs. Rava's claim of imposing lashs on another). 2 - Conspiring witnesses are only deemed such when other witnesses come forward to establish that they couldn't have witnessed what they claim to have witnessed - with testimony about the witnesses themselves, and not about the event they are speaking about. And then witnesses can come forward who knock down the witnesses who claimed the witnesses were conspiring - and reestablish the original testimony. And so on for 100 sets of witnesses. Also, Rava introduces a number of cases where the witnesses are faulty and problematic, but not conspiring. Which is difficult, but not as bad as the conspiracy of conspiring witnesses. 3 - The penalty to the conspiring witnesses - and when they would experience "as they conspired to do to another." That is, their execution would only kick in if another's life was taken because of them. But the halakhah also seems to balk at imposing the death sentence on them, after their victim has been put to death - to the distinction to the "final judgement" with regard to the victim, not actually putting him to death.