Don't move through the buildings on your left instead take the longer route to the right where you will find a safe. When he is dead it's just a case of slowly picking off the remainder. When you are ready, open fire on the unaware collector up high on your left. You are safe here, but your team will be in the line of hire. Quickly move around the corner and follow the wall all the way to the end where you can take cover at the base of the stairs. Grab them both before examining the husk for a cutscene.

There is a datapad in this area and a dead collector with a heavy skin weave upgrade. The central path is the safest for you since the collectors don't like to flank at this stage in the game. They won't be able to hit back but if a second husk attacks immediately back out. A good way to conserve ammo when fighting husks is just to melee. Dispatch of them here before moving up to deal with collectors. These things will kill you in moments on Insanity but are almost completely harmless on anything lower. When you drop down the point of no return and more collectors fly in, immediately head left and move to the far corner.

You will need it all to make it an easy fight. Don't use your Heavy Weapons for this entire level until the final encounter. Make sure you grab the power cells and datapad. It's quite crowded so watch out for flankers. You should be able to take them out without any difficulty, but don't move down the steps as you fight as a few more will fly into the battle. Having someone with Incinerate also helps greatly so the perfect combination would be Miranda and Mordin. If you didn't take her, you can restart the mission from the load screen. You will really need someone with that power for this mission. If you don't have Warp yourself, make sure you take Miranda.

Mass effect 2 horizon mission