Editing Warhammer 40,000/8th Edition Tactics/Adeptus Mechanicus (section)

=== Your First Army Composition ===
Depending on your preference, you'll either be running a combined arms list, or a Heavy Support list. Adeptus Mechanicus are very Command Point hungry, so running at least one Battalion detachment is always worth it, which means you'll need 2 HQ choices and 3 troop choices. Before you start buying models left and right, consider which Forgeworld you want to run. If you want to run Mars, you will need to purchase Cawl, if you want to run anything else, one Techpriest Dominus and a Techpriest Enginseer will do. Next, you will need to run a minimum of 3 troops. If you want to run Vanguard heavy lists, I suggest you go with either Stygies VIII or Graia. Run three 10 man squads of Vanguard, preferably at least one squad full of Plasma for marine/vehicle hunting. If you want to run any other Forgeworld, I suggest you run 3 minimum squads of Rangers or Vanguard instead, just to comply with the troop tax. You now have your Battalion ready, and you've got 8 Command Points to play with.

Your Battalion Detachment has room for 6 elites, 3 heavy support, and 3 fast attack choices. Rather than using these slots, however, consider starting a Spearhead Detachment for an additional Command Point. Please note that you can give this detachment a different Forgeworld dogma, should you so desire. The sweetest Adeptus Mechanicus units are found in Heavy Support, and you'll want to run lots of them. It will require 1 HQ choice, which you can fill with a cheap, barebones Techpriest Enginseer, and a minimum of 3 heavy support choices. At the very least, you'll want one Onager Dunecrawler armed with an Icarus Array to deal with fliers. The rest is up to you. Want Kastelan beep boops? Go to town. Want more Dunecrawlers? Go crazy. Unless you are planning to run more than 3 units of Infiltrators, Dragoons or Electropriests, just keep them in your Battalion Detachment.

Another option is to simply try and maximize your Command Points by running two full Battalions. It's fairly easy to achieve since Techpriest Enginseers is an HQ choice now, and cheap as can be, clocking in at a measly 30 points. Get two additional Enginseers, and three troop choices (small or big, whatever suits your need, however 5-man ranger squads are now only 35 points), and you'll have all the slots you'll ever need, plenty of troops for objective capping, and 12 Command Points to use. Besides, having 2 additional Enginseers to repair your units isn't a bad deal, to begin with.