I can add `forbiddenArmorsInNextStage` list to either starting conditions or to enviro effects.
Option 1/ If added to starting conditions, it would mean armors are banned in stage 2, 3, 4, etc. Or in other words, in all stages except stage 1.
Option 2/ If added to enviro effects, when moving from stage A to stage B, the list of banned armors would have to be defined already in stage A.
Defining it on stage B is not possible, because the terrain (and thus potential enviro effect) depends on RNG, and the RNG dice are rolled too late for this feature to work.
Option 3/ both of the above
Which option is better for you? Probably option 3?
-----------
Also, what should happen if you kill all aliens in stage 1, but you only have banned units left? Can you move to stage 2? Or do you lose automatically? Something else?