Call and Response: The Bulwark

Go to the Watchtower at the Cold Rushes
First things first, make your way west from The Bulwark. You'll find Kivva there. Chat with her to let her know she's needed back at the camp. Unfortunately, Ezzeko, who's stationed at a different watchtower, isn't responding. So, your next move is to head north towards that mountain watchtower.

Go to the Watchtower at the Top of the Mountain
Once you arrive at the base of the mountain, it's time to start climbing. Activate your Focus by holding [R3] to highlight any climbable ledges and handholds. Follow these paths all the way to the top. When you reach the summit, you'll be immediately confronted by two Apex Skydrifters. You'll need to take them down before you can look for Ezzeko. These machines are weak to Frost Ammo, and they have several critical weak points you can target: the Tracking Container, Scanning Unit, and Boosters.

Examine the Corpse
After you've dealt with the Apex Skydrifters, approach the watchtower. You'll find the body of a fallen soldier. Press [Square] to examine him. As you do, you'll hear a call from Kivva. It sounds like she's under attack. Your next objective is to glide back down to her watchtower. When you arrive, you'll find four Frost Glinthawks laying siege. These machines are vulnerable to Shock and Fire Ammo, so use those to defeat them. Once the Glinthawks are down, speak with Kivva one last time to complete this Errand.