My team is about to board a Sisters-held Blackship that has been overrun by rogue Psykers. I'm looking for some input into what all the team would encounter.

Currently I have:

Blocked Door/Bulkhead that they need to tech past, or Melta.

Rogue Psyker - fight

Random psychic phenomena like a lost IG 'ghost' squad that keeps reappearing but has no effect on the mission.

Warp-Walking from one ship to another

Capture not kill orders for some Psykers

Rival Inquisitor (taken from Purge the Unclean)

Warp Portals that release some lesser demons

environmental hazards like pipes bursting and hallways collapsing

rescue/exfiltrate some IG

If you have a librarian with the Psyniscience skill, he could detect the use of some psychic powers. When reaching the location of the disturbance the team finds a few officers of the ship trying to kill the rogue psykers. With orders to capture some psykers, this opportunity cannot go amiss. Does your team believe the officers will succeed in killing the psykers and are required put an end to them in order to capture the psykers. Or does your team aid the imperiums officers and kill the psykers in the hopes of finding others to capture.

The former choice could have a psyker think he is about be captured again and lose his mind which would open a warp gate and allow daemons onto the ship. The psykers unbeknown to the Kill-team could be imperial sanctioned but are captured anyway. Just before the psykers are captured they make a run for it, forcing the Kill-team to follow into unknown territory or letting them get away.

The latter choice of saving the officers could result in the officers aiding the Kill-team by opening doors etc. The officers might have been the bad guys and the psykers could have been sanctioned by the Imperium to aid in the capturing of more. The group of captured psykers could attract a lot of deamons to their location, do they kill a few to save themselves?

You could have a varying amount of the above, maybe a more powerful psyker manages to get away while the weaker ones where captured, which still attracts daemons so do they keep the group of weaker psykers when killing them and finding the stronger one would reap a greater reward but be a higher risk as their hostages slow them down, so must be eradicated in order to pursue him.

mad battle sisters convinced the marines are corrupt...or a battle sister rescue team unknown to the marines...