Yup yup... Custodes power scaling, especially during the Horus Heresy (to my knowledge), is quite inconsistent and varies pretty heavily based on the author. Not to mention that some of the early editions of 40K actually stated that Space Marines could probably beat a Custodian 1v1, back before GW decided to make the golden boys the demigods they usually are portrayed as today... what you get from stories being written by different people at different times during different editions of the game, I guess. I'm not kidding, it was once (now retconned) canon for most people to believe a Space Marine would kill a Custodian just by virtue of battlefield experience alone, seeing as Custodians didn't leave the Palace. Today, though Custodes are more consistently portrayed as godlike badasses, Norn Emissaries will still use golden heads as soccer balls (but if it can also annihilate pretty much all of a chapter's dreadnoughts and half the chapter, I guess it's only fair it can kick a Custodian's head off. Bugs got revenge for that one time a single squad of Custodes killed off an entire Hive Fleet tendril and I think the Swarmlord in close combat...).

Theorically.

Also, I just realized that the Librarian probably just sensed there were more than 5 Custodians on the main ship, and that they would've just won by teleporting their boys onto each ship's bridge.

​@@darthnox8286now im just imagining 5 Custodian Terminator teams just standing in the teleportarium just praying they can fight again