When the contingency captures a planet, they seem to get stuck in that system, and the pops on the planet aren't purged like they used to be, so it's just occupied perpetually until someone lands any number of troops. (I took back about 7 planets and never saw any defensive armies.)
When a colossus uses the shield weapon on a sterilization hub, it doesn't count as being destroyed, will still show in the situation log, and will prevent the crisis event from progressing. Furthermore, as far as I know, once shielded the planet is indestructible, meaning finishing the event becomes impossible.
When a colossus uses the shield weapon on a sterilization hub, it doesn't count as being destroyed, will still show in the situation log, and will prevent the crisis event from progressing. Furthermore, as far as I know, once shielded the planet is indestructible, meaning finishing the event becomes impossible.
