The MEC Soldier is a new class added in the X-Com: Enemy Unknown expansion X-Com: Enemy Within. These soldiers are made by converting a soldier of another class to a MEC Soldier and equipping this soldier with a MEC. These soldiers follow a different class progression than other classes, but gain an additional ability based on what class they originated from. Because this class gains abilities from its base class, actual class, and from the MEC it is equipped with, there is a lot of variability in possible builds. The following are some of the best builds you can make for a MEC Soldier in X-Com: Enemy Within.
The Wall – This build is based on making your MEC Soldier as durable as possible. To this end, you will choose the following skills: Automated Threat Assessment, Damage Control, One for All, Repair Servos, Absorption Fields. This combination will reduce damage dealt to this character, give increased defense while on overwatch, and allow the soldier to act as cover for human allies. This last ability is why you might choose a support character to turn into the class, though a heavy is almost certainly the best choice. Your selection of tactical subsystems doesn’t matter much, with the exception of Restorative Mist, which is critical. Send this character out front and put snipers behind it. It will allow you to provide mobile cover to your snipers and this soldier is nearly impossible to kill, especially if you have a support character nearby.
Strike and Fade – As the name suggests, this soldier can make a massive alpha strike and then retreat to safety. The incredibly high health of your MEC soldier allows you to this even better than the assault class this troop converted from. Choose the Vital Point Targeting, Jetboot Module, Expanded Storage, and Absorption Fields to support this build. The last ability combined with Shock Absorbent Armor from having been assault will keep this soldier alive, while the other three skills will give this MEC massive mobility, improved damage, and big guns. Increase that mobility and damage potential by selecting the Kinetic Strike Module, Grenade Launcher, and Proximity Mine tactical subsystems. This character will be able to move almost anywhere on the battlefield at high speed, and hit an enemy for as much as 20 damage. Then, when the character needs to retreat, proximity mines and grenades can be used to cover that retreat. This is a perfect build for targeting high priority enemies.
Turret – This build is primarily designed for maps with minimal cover where you can allow the enemy to come to you. Your MEC Soldier will become a non-moving turret that fires at anything that moves. Ammo is a major problem with this build and you absolutely need to build Ammo Conservation in the Foundry to make it work. Start with a sniper and then select the Advanced Fire Control, Damage Control, Jetboot Module, Expanded Storage, and Reactive Targeting Sensors skills. If you can afford to assign a support character to this soldier, you can replace Damage control with Vital-Point Targeting for a nice damage boost. The two tactical subsystems that matter to this build are Restorative Mist and Proximity Mine. Your general strategy will be to leap to a good vantage point, drop proximity mines in whatever direction you expect the enemies to come from, and then go into overwatch every single round. This character will often kill enemies before they act and devastates flying enemies.
Kamikaze Drone – Despite the name, this build is not supposed to die. In fact, to make it really work, you want to pair it up with a support character that can keep it alive and it best converted from a support class as well, though an assault character also works. Select the Vital-Point Targeting, One For All, Repair Servos, and Reactive Targeting Sensors skills. Then equip this troop with a MEC that has the Flame Thrower, Grenade Launcher, and Electro Pulse tactical subsystems. The purpose of the kamikaze drone is to run into large groups of enemies and explode, either with Flame Thrower or Electro Pulse, which will be more effective. The support should stay nearby and in cover. When the kamikaze drone begins to take too much damage, it should use One For All, allowing the support to use it as cover in order to heal it. Health will dip dangerously low with this build, but if enemies are clumped, as they often are, you will be able to deal more total damage than with any other build and potentially disable robotic enemies as an added bonus.