Here on Srs Gamerz you can find the full video guide for Mass Effect 2. The run is done on Insanity mode on a Vanguard (my favourite class in the game). The walkthrough consists of showing each individual mission, with a brief explanation of why I choose certain weapons and certain companions, and then I get right on the action and show you how I play the game with the Vanguard.
Using Your Skills and Those of Your Companions
Your companions will never do as much damage as you do. However sometimes they are able to take down enemies on their own. Treat them well and don’t leave them alone. They’ll feel lonely. It is important that you also use their skills so that you can get through the hurdles that missions throw at you. Don’t just let them use the skills whenever they want. Place them on your skills bar and use them yourself as if they were your own skills. If you so wish, you can go to the Options screen and disable the automated use and so that only you decides when to put them to work. It’s a good idea if, for example, you do a lot of skill-chains (for example Pull > Detonate with Warp) and you want to make sure your companions didn’t use the skills before. I personally leave the automated use on, because they don’t fire their powers that often and it’s rare that they have them on cooldown when I need to use a skill chain. It does happen sometimes though. Also your companions often make a good call and use them in appropriate moments.
When using any power, remember this: You will put every other skill you posses on cooldown. Ammo powers have a shorter cooldown, allowing you to use your other skills a bit earlier.
You don’t put your squad’s skills on cooldown when using your own. So you can use your own pull skill, and then tell Miranda or Thane to use Warp on the enemy you pulled to detonate the biotic effect and do more damage. Or you can fight an enemy that has a biotic barrier, and unleash double warp on him, thus effectively destroying the biotic barrier in the space of 1 second. Same goes with shields, if you happen to have two companions with Overload (or if you are using a class with Overload + a companion with that skill) you can double Overload and so on.
Some companions, and some classes that you can play, have some special powers called ammo powers. Don’t underestimate them. Like all skills, once you reach level 4, you can evolve them 2 ways. One is a more powerful version that only applies to the character who has the skill. The other is as powerful as level 3, but it applies to the entire squad. Unless you own the ammo power yourself, I advise to always spec your companions for the squad version of that power, because that means that you can use it yourself.
Example 1: Vanguard has incendiary Ammo. My personal choice was to spec my Shepard to give squad ammo. So now every single squad member can benefit from it. There are other squad members that have Incendiary Ammo as part of their skill set, you simply don’t put points in that, and use those points for other skills.
Example 2: Zaeed (if you bought the DLC) has Disruptor Ammo, which is good against shields and synthetic targets. I specced him to give it to the whole squad. Now when I go into a mission with my Vanguard knowing that I need to destroy many shields and/or mechs and Geths, I’ll not use my Incendiary Ammo (it’s weak against synthetics) and I will bring Zaeed and have him give Disruptor Ammo the the whole squad.
Note that if one of your squad members dies, and you are the one supplying the squad ammo to your companions and yourself, you need to reapply the squad ammo when your squad member is ressed or becomes available again after a battle. But if one of your squad members who is supplying the ammo power dies, you retain the power.
In example 2, if I tell Zaeed to give Disruptor Ammo to my entire squad, and then he dies, me and my other companion will still have the buff. Of course, when Zaeed comes back into the fight, he needs to reapply the power for his own weapons.
While in Mass Effect 2 you don’t see stats on your weapons, you should use the descriptions to know what’s better. Mass Effect Wiki has a description for each weapon, showing you the rate of fire, the base damage and what they do most damage against. For example it will tell you that the Geth Pulse Rifle does x1.35 extra damage against shields and biotic barriers, but it only has a multiplier of x1.15 against armour. That means it’s a good weapon for Adepts and Vanguard classes as they don’t have disruptor Ammo or Overload to get rid of shields. Although Adept does have Warp, which is effective against biotic barriers (and armour).
In other words, weapons in Mass Effect 2 are situational.
Simply because you found a weapon later on in the story line, it doesn’t mean that it is better than what you had before. However if a weapon says, “This is a direct upgrade from [weapon name]” then it means that it IS better. For example the M-9 Tempest Submachine Gun is a direct upgrade of the M4-Shuriken. Meaning that once you get your hands on the Tempest, it is unlikely that you will want to use the Shuriken over it. However the Locust Submachine Gun, is a weapon that you use in different situations, and whether you’ll use the Locust or the Tempest depend on your personal playstyle and the mission.
Squad companions have no accuracy issues.
So while you might feel that the Tempest has high recoil and bad accuracy if you keep your fire button pressed down at medium range, Companions will not have issues hitting enemies with it.
General Advice for Vanguards
At least when playing as Vanguard, you will notice how much of a difference upgrades will make. The game actually becomes easier as you progress through it, rather than harder. You will have missions, i.e., all the missions that have Collectors in it, that will still be harder no matter what class you use, but in regards to the other missions, you will find that the more upgrades you get, the easier they become.
You want to put points in Incendiary Ammo for the first mission you do, i.e. when you recruit Mordin, because Krogan and Vorcha have high health regeneration, Vorcha being the worst. If you don’t make large use of Warp and Incendiary Ammo (which both stop health regeneration) by the time you go into cover, reload and get back out, the Vorcha you were shooting at will be back at full health on Insanity mode. You don’t need to keep putting points in this skill after this mission, but you will need to do so at some point.
After that mission, start maxing your Vanguard passive ability (Assault Mastery) and your Charge. Since you will be chain charging, the best evolution for your Assault Mastery on Insanity is Champion, because it reduces the cooldown of your biotic powers. Even though you will hardly use any of your other biotic abilities, you will want Charge to be off cooldown as soon as possible.
Don’t just “do the Vanguard thing” of using a shotgun and charge blindly into your enemies to shoot them up close. At the beginning of the game you don’t have enough upgrades, so you won’t be able to withstand enough damage if throw yourself at a group of angry mercenaries. Remember, this is Insanity mode. Enemies hurt. Wait for upgrades, then play Rambo if you are so inclined.
Just play cautiously for a while and once you have both your Charge and your Assault Mastery maxed, you will be able to grab that shotgun and start chain charging, if you like. By that time, you’ll also have collected upgrades so it will be easier to do. Yet, again, if you find yourself dying a lot doing that, you need to wait for more upgrades. Until you reach that comfort zone, just stand back in cover and shoot with your SMG (or Assault Rifle when you learn to use it training later in the game). If you don’t like shotguns, but you like to chain charge, it’s perfectly viable to do so with an SMG or an Assault Rifle too.
Once you have Champion and Charge, go back to your Incendiary Ammo and max that. I usually evolve it as Squad Incendiary Ammo. While your companions don’t do as much damage as you do, they still do help and it’s nice to give them an ammo power if they don’t have one. I tend to also spec my companions to give squad ammo so that I can use theirs.
As a special skill, i.e. one of those that you get by doing the loyalty missions of your companions or by playing Mass Effect 2 a second time, I use Geth Shield Boost and evolve it as Improved Geth Shield Boost to get the 10% weapon damage buff.
In regards to companions, whether you like it or not, Miranda is always the best choice. She has something for everything. She has Overload for shields and has Warp for everything else. Aside from that, she also has a squad buff that increases health and weapon damage for everyone. It is however possible to do missions without her, I am just saying that if you are a min-maxer, then you’ll always bring her. The second companion is very much situational.