#2 The Fiend's victims
Since his return as The Fiend, Wyatt has caused pain and suffering to many Superstars. He has a wall in his Fun House dedicated solely to such victims. His victims include the likes of Finn Balor, Seth Rollins, Kurt Angle, Mick Foley and many more.
I'm almost certain that this match will not take place at the venue and will be pre-taped outside. In this case, during the match as and when Cena is made to go from one room to another, The Fiend may vanish out of sight and a legend such as Mick Foley or Kurt Angle may appear for a quick second telling Cena to run away.
Using legends that have fallen prey to The Fiend would only build him up further and depict him as a major threat to the WWE Superstars. Also, such mind games and trickery would not only confuse Cena but also would result in good television content for the fans. WWE has its own studio that it can put in use for this match.