The Fourth and final quest Bashar will send you in is at the Hospital. It is another hacking quest.
If you dont have Hacker Traits return to Zia, Hugh, and or Slim to help you with the quest.
Bashar will send you to the general hospital in Rookwood to hack the terminal on the roof.
Get to the hospital and get to the top of the roof. Kill the security that is waiting. Once done head to the parrot and talk to it. The hacking will begin.
Once the hack starts multiple witches will spawn you dont have to kill them all. Just wait long enough till you get dialogue to go see Bruce at the top of Wayne Enterprises.
Head to Wayne Enterprises and go to the top Bruce will be waiting for you at the top in his batman costume.
Let the dialogue play then you will have to kill Batman. Once you have successfully killed him he will drop his Elyntra (cape). Joker dialogue will appear and you will have 35 seconds to fly down to the diamond sword to kill the Joker. Equip your Elyntra as a Chestplate jump off the building towards the diamond sword.
Once the Joker is killed return to Bashar and witness a surprise!
IF YOU ARENT ABLE TO KILL JOKER IN THOSE 35 SECONDS TRIGGER THE QUEST AGAIN BY TALKING TO THE PARROT ON TOP OF THE GENERAL HOSPITAL.
General Hospital: X:-723 Y:63 Z:732
Wayne Coordinates: X:-796 Y:64 Z:643