The fight to take over Queen Anne district (District Showdown) will be possible only after D.U.P. forces control less than 30% of a district. Go to the place marked with a phone icon. It would be best to use one of ventilation shafts there, so Delsin will get to the metal balcony adjacent to a large billboard. Now make a call to start the battle.
Try to get to one of rooftops of adjacent building as soon as possible because D.U.P. forces will soon appear in the area and it would be good to start the battle with some powerful ground punch for example (I recommend using Comet Drop). Once the battle begins focus on destroying enemy armored vehicles (Cinder Missile - R1 can be very helpful here) and eliminating opponents with supernatural powers (try to kill them from a distance). Watch out for snipers (laser sights) trying to constantly move. Fight until all enemy forces are defeated.
Rewards for taking over Queen Anne to:
- Unlocking fast travel
- Getting rid of all D.U.P. soldiers in the area
- Unlocking Delsin's unique clothes - Agent