The Legions Astartes faction for the upcoming, epic scale Legions Imperialis game focus on heavy infantry and tanks. These will be made up of Detachments (similar to units in Warhammer 40,000) for which there will be datasheets.
There will be Detachment Cards with one side used for building the army and the other for playing. The building side will show point costs, standard size, and upgrades. The playing side will show stats, weapon proviles, and rules.
You can combine Formations (groups of Detachments) from different Legions to combine tactics and special rules.