Equivocate is a second level Shattered mirror counter.
You tie yourself to an opponent, so that spells and effects hit both of you for a round.
Question is, you target enemy with this counter, he gets hasted by a 5th level caater. Do you get Haste for a round while the counter is active, or for 5 rounds, since Haste was cast on you?
It lasts 5 rounds. The counter makes it target you, so he cast haste on you. Once that's happened it behaves as normal.