This mission again concerns Cerberus attempting to thwart your attempts at uniting all of the races. They know that if you can gain the support of the krogan, you might just have a chance of defeating the Reapers. This is not what they want. To that end, they have commandeered a ground-to-space cannon on Tuchanka and are now using it to obliterate the fleet surrounding the planet so that a bomber can swoop over and destroy the krogan forces.
When you leave the dropship, head forward to find a group of Cerberus soldiers. They don’t know that you’re here yet, so score a free kill or two and eliminate the rest of the enemies after their force is weakened. Several Guardians, Combat Engineers, and Centurions will be in the mix along with more standard fare. Try to make your first stealth kill or two one of these more powerful enemies, as it will make the going easier for the rest of the battle. The Combat Engineers especially need to go down early. Take cover and return fire to the Cerberus troops. Heading into the side room will allow you to flank around them. Order your squad to remain at the frontlines while you head around the side unnoticed. Take out any remaining Combat Engineers first, along with the turrets that they have deployed. By now, the rest of the troops will surely notice you.
Kill the Centurions next. Quick headshots or powerful Biotics will do the trick in a pinch. If the Guardians begin to advance on you, use Pull or the Scorpion Pistol to render their shields useless. Mop up the normal enemies afterwards. When all of the opposition is gone, search the computer to find the Old Grid Schematic, an item needed for a side quest on the Citadel. You can also find the Armax Arsenal Gauntlets and some medi gel here. Activate the console when you have collected all of the items, and more Cerberus troops will attack.
Hunker down in the back room and take them out as they come. Use a similar strategy as before, as you will be fighting in the same area. When they are dead, you will have to restore power to the area before taking control of the cannons. Head back to the burned out bunker near the dropoff point. You will have to counter-snipe the Nemesis snipers that litter the area. Kill the rest of the stragglers on the ground, shoot the locks on the power conduits, and activate them. Head back to the control room, where yet again Cerberus will have dug in. Combat Engineers will already be in the process of setting up turrets, so rush them and kill them before they can finish. Use your squad to cover you. Take up a position alongside your squad-mates in the control room to fend off the other enemies. Activate the cannons when they are all dead to shoot down the bomber.
