Delsin mentions to Reggie about trying to find the locations of some more Core Relays, which will be displayed on your map. You’ll have to go to each location, take out any DUP guarding the devices, then break open and drain them to gain new abilities. The one in the northeast gives you Comet Drop, the southeastern one grants Cinder Missiles and the one in the southwest gives you Sulfur Bomb.
Once you drain the Core Relay and get each new ability, you’ll get a chance to test it out against some DUP soldiers. The Comet Drop is best used when jumping off of high buildings, the Cinder Missiles is great for groups and vehicles, while the Sulfur Bomb is a fantastic way to stun enemies to Subdue/Kill them.