Genesis Legions can summon an unlimited supply of Auxiliary Legions, while Auxiliary Legions can only summon one fellow Auxiliary Legion. This will be reviewed over time to ensure inflation remains in balance with usage.
There is a chance on summoning failing that is tied to the number of Legions crafting versus the number of Legions summoning. If your summon fails, your Legion will be in stasis for two days, unable to complete other tasks. Your resources will be returned to you with the Legion at the end of the stasis period.