In Peoria, set the game to "Easy" mode, and fight the insects in what manner you see fit. When your squad reaches the first room with laser turrets, arm them with only melee weapons (preferably monkey wrenches, diamond tipped spears, microsledges, or whatever else is available). Have half your squad surround each turret. You should definitely have Stoma in your group. Also make sure that everyone has a relatively decent melee weapon skill. It is not necessary but is helpful. If everyone surrounds the turrets correctly (in the first room with them; for the other individual turrets at the ends of halls, etc., use all squadmates), and they all attack on targeted mode, set to either CPU or sensor, you can destroy the turrets in about ten minutes with no loss of life or heavy damage. If done correctly, the turrets will explode after awhile. Each contains roughly 600 to 630 Fusion Cells. By the end of the mission, if such maneuvers are carried out, you will have several thousand Energy Cells for later missions. Note: Do not try this in the Brahmin Armor Special encounter.
