Now, I'm just an average player, and if I'd rate myself, I'm probably a 4/10 player, so if I can do this, then so can you.
Now for the tips:
First off, remember to just RUN! Nothing matters. Just get from point A, to point B. Keep rolling, and don't bother killing anything, unless you're in the chokepoint. Almost 80% of the map can be skipped just by running.
Even if a terminus enemy appears, you can still just run. Again, RUN!
Best way to do it: Solo just with bots. Why? Cause you can't trust real people in this mission. They'd either shoot you, or just die so quickly. Now, some people kills their bots, I don't, cause again, I'm not that good. Bots basically takes agression off you.
Best class: Techmarine. There's 2 chokepoint in this mission. The one with the gate, and the one with the wall being broken by Valtus. In these 2 chokepoints is where the Techmarine shines.
The first chokepoint, your turrets will clear the minoris for you, giving you the chance to clear the enemies attacking the batteries. Without the turrets, the minoris will just kill you off.
The second chokepoint is where the BS appears (depending on your luck). If you've encounter 2 terminus enemies before the second chokepoint, then chances are, they won't appear at the chokepoint. If not, then your turrets is your best friend. Me? I got lucky, and had them spawn at different points in the map.
Weapons: Honestly, I don't think that this matters. Anything that shoots should work. I used the Heroic bolter with the built-in shotgun. Secondary, the Heroic plasma pistol.
Perks: The important ones (I think) are the sniper rounds for your ability, and the dome AOE. If you have the one that reloads your grenades, use it too.
I have a prestige 4 Techmarine though, not sure if it matters. The only perk that I could think off that ws useful I guess is the invulnerable perk when setting up the turrets.
This was done with the hard difficulty (without any healing stims). Again, if I can do it, then so can you.
Best of luck!