Mass Effect

It can be done on any difficulty:) After you complete every map with the best score you get access to this special mission. It is not really that difficult. First download the data from the thing which looks like a bomb from Eden Prime (it's somewhere in the middle of the area). After that you have to survive a 5 minute attack. Try to hide on a staircase where you started the mission. You can activate the turret there to help you. There's also a door that you can see from the staircase which you can shut (put on BARRIER and run for it:)). After 5 minutes mission ends and you get the achievement.

I just got this achievement during my insane play-through which led me repeating it quite many times until I got it.

1. You need rapid fire power. Enemies are rushing at you all the time, they don't stop for cover and doesn't try to spare their life. Best way to deal with them is to kill them as fast as possible, before they get on your skin.

2. Enemies respawn without delays, constantly. When you kill one, it respawns practically instantly back from their starting position.

3. Last minute is actual trial can you make it or not. Before that it feels quite easy.

When you first start this mission there are half a dozen turians waiting for you. They use some snipers & engineering at you, and there is one anti-tank rocketguy waiting you across field you see when you first enter from door. So dodging right away is needed, that rocket can oneshot you, and snipers do miracles to your shields.

Deal with these guys with time, no need to rush and these wont respawn yet. After you have killed these guys, take your time to activate both ground to surface guns at both staircases. One is at staircase right where you started, another is across field. You don't have to worry about these in first encounter as they don't fire during that even if activated.

After this go position your squad in proper place. I found best place to be other side of that simulation area, over brides. Looking from start, on left side there are few boxes in corner, then there is middle some boxes and right side is without. Go order your squad to be put behind middle boxes. That'll give them some cover. You take place at left side, hiding behind those boxes. But before you take your cover, go retrieve data from center of that map. Run then to your safe spot.

Few words from enemies which are coming. They are spawning at map side you started. There are staircases at back of that map, on top of those spawn turians who are keen to use sniper rifles. Below that is somekind of gateway/huge doorway, in front of that spawns two anti-tank turians. Then both sides of staircases spawn 3-4 regular turians constantly.

When you are positioned as I have given example, there is constant flow of regular turians over bridges towards your squad members. They don't usually pay much attention to you, if you don't shoot them head first. Best way is to let them go past you and shoot them in back. Occasionally some guy wander towards you, but you'll be fine with so little resistance. They are mainly consentrated to your teammates who should be taking care of themselves.

Anti-tank turians are put first ~3 minutes of mission, leaving you quite safe from their rocket fire. But after that they start advancing, and at least on last minute they start push towards you really heavily. Keep an eye for them, and take them down or even better crowd control them (so they just don't respawn right away). Last minute feels like turians are accelerating their speed, so you must consentrate your special powers and other aids for last moments.

Played this with lvl 52 Adept, and used Ashley and Wrex as companions. Both were using assault rifles, I was using just pistol. When they got run by turians I used singularity or lift to give them some room, and used statis to anti-tank guys I saw near us. Push was reserved mainly for dudes who ran at my hiding place, though melee with pistol was quite efficient against them too.

Wasn't easy achievement in insane difficulty, I sure appreciate this achievement greatly.

I completed this as a Level 48 Soldier on a Hardcore playthrough, right after leaving the Citadel post Virmire. Note - this is the last possible chance to complete any side missions. If you have things to finish up, do NOT go to Ilos. There's not really much more to add here, but I wanted to share my squad setup since it's only briefly been discussed.

Like kerbe, I also went with Ashley and Wrex for their combat prowess.

My whole squad, Shepard included, used the HMWA VII assault rifle with the best Shredder Rounds I had available at the time (35-40% damage bonus to organics). I further customized all the weapons with Frictionless Materials mods to limit the amount of overheating. My Shepard was able to sustain an infinite rate of fire with 2 Frictionless Material mods.

For Armor I didn't go to great lengths to scour the galaxy for the best/heaviest armor. Shepard used Colossus VII (medium), Ashley used a medium armor with ~450 shield buffer (name escapes me at the moment), and Wrex had Battlemaster IX (heavy, I think). The armor isn't as important as the mods you use to customize it in my opinion. I recommend any high level mods like Medical Interface that will provide some sort of increased health/shield regeneration or boost. With the proper mods....and I apologize that I can't recall specific names off the top of my head...I was able to complete this achievement on my first attempt without having to revive anyone with Unity, and I only used a single medi-gel.

The key to this lies in the preparation. Make sure your squad is appropriately equipped and I don't think you should have much problem. After getting properly outfitted, I did something similar to Yuhans in that I holed up on the staircase I started on. Prior to downloading the data I activated BOTH turrets. Once the attack begins I let Ashley and Wrex stay out front near the top of the stairs while I hung back near the door you come through to start. They will be protected by railing as cover and do a good job of picking off enemies from the left and center. I focused my fire on the stairs themselves which served as a great choke point for enemies trying to rush the squad. With no overheating and constant fire I was able to suppress them very well. Periodically I had to aim out across the map and take out a rocket firing turian. And of course, be on top of your squad status for dipping shields and health. Note - Ashley can shield boost and Wrex has barrier.

So to summarize - preparation and CUSTOMIZATION. Mods to keep your weapons firing and your shields up and you should have a tremendous advantage!

Quick and easy guide for this achievement!

Think you should wait until you reach level 16 or over for this one as it is hard if you play as a lower level..

How to get the Mission! Just skip this part if you already have the mission option...
*You have to first complete each of the scenarios with the winning score/time and Ahern (the Captain) will tell you about this other scenario that has been made and he wants you to try it and you agree because this is the mission to get the achievement. If you want more info on the scenarios check up my other guide ;)

So once you start this mission you will need to activate a timer in the center of the area you play in so just BEFORE you go to activate it, there are two huge guns that you can also activate to help you out. Activate the one thats at the right as soon as you walk through the door you spawn at to give you a little cover to activate the timer. So you have to survive for 5 minutes so just camp at the place you spawn at once the timer has been activated. Your choice if you want to activate the other gun on the opposite side of the gun you just activated.

Make sure you and your team mates are suited up with some proper armor and guns to do this and you'll have no problem at all.

I hope this guide helps and Good Luck :)
Sorry for any spelling errors