A wrinkle that hasn't been in the John Cena and Brock Lesnar series is a special guest referee. There are definitely matches where a guest referee adds to the event and puts a new dynamic into the storyline. You can't just throw in any special guest referee at random that doesn't make sense, so far the fourth installment of Cena and Lesnar, they need someone special, someone who is a familiar name, someone who has been a special guest referee on the biggest stage of them all. That man is none other than former WWE wrestler Ken Shamrock. There are several different reasons why Ken Shamrock would fit in well here. First off would be his ties to the sport of MMA where Brock Lesnar has excelled in. The other would be his past experience as the referee of Stone Cold Steve Austin v. Bret "The Hitman" Hart at Wrestlemania 13. Even Austin mentions in one of his most recent podcasts that Shamrock did an excellent job as a referee in a big match at the biggest pay per view of the year.