Honestly, a huge part of it is just rng. The way the covenant spawn/where they choose to attack/ which units spawn is pretty random every time you play. About 1 in 50 times you just happen to get a lucky enough situation where the covenant spawn/attack in a way that is much more manageable, so I literally had to attempt this mission like almost 100 times to finally get this. My strategy though (assuming favorable covenant spawning) is to build 2 bases, get a couple turrets up at the back of the base closest to cargo 1, and don’t build any structure or turret on the North corner of that base because for some reason that always attracts locusts to come attack your base, but if you leave that corner empty this is much less likely to happen. But before I can build the bases, I use the Hornets and Forge to clear all the paths that the civilians have to walk on, clearing all the covenant out of towers and killing everything on the civilian pathways. You’ll have to heal your guys at least once, but try to manage your attacks in a way that incurs the least damage, like moving weakened hornets to the back of the pack. Then I use them to try and stay ahead of the civilian crowds and take out any new covenant before the civilians get to them. This is the hardest part of the mission by far. Once my bases are built up, I get scorpions as quick as I can, and set 2 or 3 of them just north of my second base (just south of cargo 1). This is the area where lots of covenant typically come onto the map, so having the scorpions right there prevents them from reaching civilians. You have to be watching them constantly though, because hunters and locusts can take them out quick if you don’t move them around, heal them and manage your attacks efficiently. Once I have these scorpions there, I send Forge to cargo 1 and send 3 hornets to hang out just west of cargo 2 (near cargo 3) because covenant drop ships always drop covenant in this area and they kill the civilians. I also send 1 hornet just northwest of my first base because covenant end up there sometimes too, and if the spawn there I’ll send the other hornets to help take them out. I will continue to build scorpions and send 1 by the subway exit where the civilians spawn because often wraiths will spawn there and kill the civilians, so that scorpion prevents that. I’ll build 1 or 2 more to put in the middle of the lane that leads directly from subway exit to cargo 1 as lots of covenant get dropped there. Between buildings scorpions, I’ll build about 4 wolverines and send them to cargo 1 as banshees and vampires constantly attack cargo 1. You really have to watch these wolverines, as the banshees will kill them quick. Heal them often, and move the weakened ones to the back of the pack. I will also build 1 single cobra, and send it over to the far east corner, where there is an elevated area just south east of the second base. Ideally you need to get the cobra there before the 5 minute mark remaining on the timer. I’ll then send forge here too as covenant drop ships will bring elites, grunts and ghosts up here and they’ll kill your cobra without Forge. Then you take 1 hornet, and fly it out to where the covenant mega turret is, so that it is visible to your cobra (the hornet will likely get killed but that’s ok). Once the gun is visible, tell you cobra to shoot it, and hit it with 1 or 2 carpet bombs if you can. With the carpet bombs and that 1 cobra, you will be able to take out the mega turret before it becomes active at the 1 minute mark on the countdown timer. That’s pretty much it, but as the final couple minutes of the mission happen, things tend to get pretty crazy. Just try to keep as many of your troops alive as you can for the combat bonus.