Stasis Grenades/Turrets thrown while cabal is spawning at the door, makes them Immune to any kind of damage, making nightmares containments a bit of a waiting time until it progresses for the final tier. That said, prob we get less loot from it by not fully completing the previous tiers(i.e tier 1 and 2). Spawn Doors like this one: https://imgur.com/a/JFJMp6C