The Alternating Phase of every odd-numbered round is a Muster, in which new Units or Shields may be built in a faction’s Friendly Area. In the case of high-tech Units (those that cost 3E or more), the build must also be in a Home space or at a Utility owned by the building faction or a consenting ally.
Stacking limits (5 Units per map-space, 2 per Location Card) cannot be exceeded when mustering. Worker Units in Utilities do not count towards the stacking limit. Units do not need to be disbanded if the stacking limit has already been exceeded legally, such as through Worker Units leaving a Utility, but no new Units can be built in that space. Builds and disbands cannot be combined to achieve movement or interconversion of Units.
The costs, population commitments and strengths of the different Units are as follows:
|Unit||Build Cost||Strength||Population||Energy Cost per Strength||Total Cost 10 Rounds|
|Civilian||0E||1||1 P||0||2.5F 2.5W|
|Infantry||1E||2||1 P||0.5||1E 2.5F 2.5W|
|Bomber||3E||3||1 P||1||3E 2.5F 2.5W|
|Fighter||3E||4||1 P||0.75||4E 2.5F 2.5W|
|Shield||3E per level||6||0||0.5 for first level||3E|
For human factions (every faction except AI), Civilian Units can be Equipped during a Muster Phase, converting them to Infantry Units, at a cost of 1E per converted Unit. Stacking limits do not need to be considered during this conversion, because the number of Units does not change, and even over-stacked Civilian Units may be equipped. No other change of Unit type is allowed. (Like other factions, the AI can spend 1E to create Infantry Units, but the AI cannot get rid of their Civilian Units by converting them in this manner.)
Shields may also be built (3E) or upgraded (3E) during a Muster Phase. An individual Shield cannot be built and upgraded in the same Muster Phase, and only one upgrade per Muster Phase is allowed for each Shield. Similarly, shields may also be built (3E) or upgraded (3E) once during a Re-arm Bonus Military Action; this does not prevent them from being upgraded again in a subsequent Muster Phase.