Terminators, well you are in trouble. Especially because of the confined spaces. Try do abuse corners, as Terminators in full sprint have to stop to go around and a standing Terminator is much less terrible than a charging one. Aside from that I have to look at the IC.
Superior speed and manoeuvrability are key. Victus planned to do this along with stealth... he didn't expect them to come through the bulkheads that quickly.
Sabios will be on his way soon. You should built Imperial Navy vessels with halways, which only have the heigth to accomodate humans. Then Space Marines would have a really bad time trying to board them. I am intending to have that on my ship, only upscaled for marines. (Or I would, if there were many races, which are taller than Space Marines in Power armor...)
Taller than armoured Space Marines... so Necrons? I don't think you should inconvenience AND insult them unintentionally should they visit your ship.
Though on that front even rooms and doors for regular people tend to be just over 7 feet from floor to ceiling so really only taller Space Marines and those in Terminator Armour would be really inconvenienced.
Dark Eldar taking slaves from the crew... if that happens they better hope Victus doesn't see any of that or the Phoenix Lord won't be the only one looking to dish out some "punishment".
They're taking slaves aboard the former khornates' vessel, not the Sword of Orion. It's some sort of a "bribe" Jain Zar used to slightly enhance the Scourge's loyalty when they'll board the Sword of Orion - feed the predator enough and, saturated for a time being, he will even ignore a next nearby prey
Ah, okay then. Victus doesn't care about those guys. Probably worship Chaos anyway if they're still alive... or they're Armsmen from the boarding party but they probably worship Chaos if they survived that. It's fine now.