You're back in The Refuge with more Prometheans to fight! Before you head to the waypoint, take a minute or 2 to swap out one of your weapons for at least one power weapon. Incineration Cannons, Binary Rifles, Scattershots, and Shotguns, and plenty of Pulse Grenades are here to serve you. Take whatever power weapon suits you best and grab a ranged weapon to complement it. Head to the objective and activate the 2 buttons. You'll be accosted by 4 Crawlers and 1 Regular Knight, but they shouldn't be any trouble with what you're packing.
Heading out through either corridor and you'll be besieged by several Prometheans. Hang out at the exit and headshot all the Crawlers you can. You'll be relatively safe since the Knights are Battlewagons and generally won't charge you from this distance. Take out the Watchers next (try to aim for their tiny heads) and get the 2 Knights last.
When they're done, stay back at the entrance and prepare for the next wave. You'll be asked to activate more computers to get info on what happened to the Gargarin team. Once you activate one, sprint back to the entrance of one of the corridors (not the central platform with the turrent, as this draws too much fire) and wait for the Crawlers. Because you're on the side of the battlefield instead of the center, only half the enemies will be paying attention to you and you can engage them easier. If your brought an Incineration Cannon, they can easily be used on the Regular Knights and Battlewagons from a safe distance because of their short range weapons and difficulty to dodge. It goes without saying to eliminate any Watchers before taking on the Knights.
Next, you're asked to hit some buttons at the top of the level. Don't run up there just yet, hang back near the ramps leading up there and pop the Crawlers as they come down. The Knights will be isolated and can be Incinerated/Sniped/Blasted with ease. When all foes are down, press the 4 buttons.
There's just 2 more waves left. Several Crawlers, a few Watchers, and some Knights will spawn. But the most dangerous foe are the Commander Knights with the Incineration Cannon. They usually spawn Watchers as well. Be careful about attacking them and consider using a Binary Rifle to deal with them the safest way.
One more wave with only token opposition, and you're done. A handful of Crawlers and one Regular Knight. Blow these losers away, and you're done.