Head to the Dreadnought and land in its bay. You will see an armada of ships engaged in battle around it. You will have to secure the docks for the rest of your squad before you can have your selected squad-mates as backup. Head to the docking tube to reach the inside of the ship. Secure the other docks and your squad-mates will land. You will have to walk up the walls, as you will be in a zero-g environment. After securing the docks, head to your left to find the Shotgun Smart Choke Mod. Head down to the lower area and walk around to the right. Get onto the metal beam and walk all the way across it to the ladder. Climb the ladder to get to the next level, then enter the door to the right. Grab the Geth Data from the console, and then activate the docking controls to rejoin your squad.
You will receive a gun from whichever quarian accompanies you into the Dreadnought after you enter the ship proper. Grab the Arc Pistol from the ground and equip it, as it is very useful against the geth. If Xen joined you instead of Tali, she will opt to remain here for the duration of the mission and give you support via the radio. Head around the corner and into the next room. Check the right-hand corner to find the Sniper Rifle Enhanced Scope Mod. Activate the GUARDIAN computer console to the left, then head across the bridge to the right to get to the bridge controls. Activate those, and a group of geth will come out to intercept you. Take cover on the side of the walkway and wait for the Rocket Trooper to come into view. Use Overload to disable the Rocket Trooper temporarily, then open fire on it until it dies. Kill the lesser enemies dotting the area, then head across the walkway.
Turn to the right to find another group of geth, along with another Rocket Trooper. Again, take cover and take out the Rocket Troopers in the area before focusing on the lesser geth. With multiple Rocket Troopers here, you will definitely take at least a little bit of fire before you can finish them both off. Keep in mind that it is actually possible to shoot the rockets while they are in the air to avoid damage, as long as you are far enough away when the explosion goes off. Head to the right when all of the enemies are done with and climb down the ladder. Another geth will stand in front of you. Take him out with a charged melee attack to avoid spending any more ammo. Another wave of geth will emerge, alerted by your attack, and you will have to take them out.
Take cover on the left-hand protrusion by the railing. Another Rocket Trooper will accompany this wave. Use Shockwave to toss the lesser geth out of the way, opening up the Rocket Trooper for a lot of damage. Watch out for the mines that will dot the battlefield here as well. You might want to simply stay in cover towards the back of the battlefield to avoid accidentally stepping on one during the chaos. After the fight, keep an eye out for the telltale yellow glow of a mine and shoot it to avoid taking damage.
At the other end of this area, examine the holographic terminal to the right to get some information on the geth. Make a left and head down the hall to find Geth Data and the Archon Visor on a computer. Head into the next room to find the Geth Pulse Rifle Assault Rifle. Once you have collected all of the items in this area, you may proceed into the next room. You will be met with a cloaked geth, which you will have to battle along with a wave of normal geth. They will rush you, hoping to overwhelm you. Spread out towards the back of the area, shooting while you retreat. Use Tech powers to disable the geth when you can, as these are very effective against synthetic enemies. Use area of effect-based attacks, such as Nova or Grenades or Singularity, to reveal the presence of the cloaked geth Hunters. You will be able to more clearly see the telltale shimmer of their cloaks in the swath of destruction left behind by these attacks. When the cloaked enemies are revealed, unload on them.
Stick together with your squad to ensure that the rushing enemies don’t get the best of you. If you get pushed back too far, start to circle around the perimeter of the level and backtrack towards the other end of the room. If you can, use the Combat Drone ability to fool the geth, or use the Tactical Cloak ability to fade from sight, just like your foes. From there, you can get a critical melee attack or a particularly strong burst of gunfire. When the battle is over, pick up the SMG Scope Mod and the Geth Data by the computer console. Once you have them, activate the computer, along with the other one at the far end of the room.
Using the data store on the computer, Tali will be able to plan the next attack on the geth. She will hack the computer and trick the ship into thinking that there is a thermal warning, which will open up the path to the next area by using the ship’s emergency protocol features against it. A group of geth will be waiting for you on the other side of the door that just opened. Take cover as they run through. Send your squad to the left corner, where another door has opened, and follow them across. Circle around the geth to get the drop on them. When they have noticed your squad’s presence, you can loop back around through the first door and catch them in a pincer movement, or you can simply barrel through their forces from the side if you posses the strength and the powers. Classes like the Soldier, Sentinel, and Vanguard will want to take the latter option, while Infiltrators, Engineers, and Adepts will benefit most from the first option.