Starting the fight over control of Rainier district (District Showdown) will become possible only after lowering D.U.P. control indicator to 30%. Head to the place marked on the map with a phone icon (large billboard on the roof) and make a call.
It would be good to start this battle by blowing up two armored vehicles that are parked on the street under the billboard as soon as possible, because this way with a little luck you will get rid of several standard soldiers before they get away from the vehicles. When it comes to the most serious threats, first and foremost, watch for the elite soldier with a minigun. Try to attack him from a distance and as much as it is possible avoid direct confrontation with this character (do not forget that you must finish off the enemy after he loses enough hit points).
Rewards for taking control over Rainier:
- Fast travel option
- Getting rid of all D.U.P. soldiers in the area
- A unique outfit for Delsin - Epic Vest (you can change it in one of the menu windows opened by pressing Options button)