The victim was on his way home from the festival on Sunday June 29th when he became involved in a street fight with around 15 other people at 03:40 am, near to the Thaliastraße U-Bahn station.
He was so badly injured that he had to be put into an artificial coma and has not been able to speak to police.
Police are keen to speak to two young women who witnesses say gave the victim first aid next to the number 46 tram line stop.
Police are also looking for a man, believed to be Polish and called Krystian, who was also injured in the fight and treated in the AKH general hospital before being discharged on the evening of June 29th.
Investigators believe these three people may have important information. Police are asking for any other witnesses or anyone who may have seen or even filmed the fight, to come forward.