Board Thread:Warhammer 40k General Discussion/@comment-185.37.86.69-20160206091809/@comment-26420219-20160210212717

If I recall correctly the Cabal referred to Alpharius and Omegon as one Primarch-being, one soul in two bodies. As the case has never been mentionned before we simply don’t know if one Primarch could survive without the other. If Guilliman truly killed one of the XXth Legion Primarchs on Eskrador, it could fully well be that his other half would perish, even if he was half a galaxy away as their common soul was dragged into the Warp.

I could imagine something along the lines of :

"Half a galaxy away, Omegon stopped in his tracks. Leaning on the wall for support he felt a numbness crawl up his body as his primary heart stopped. ’Brother...’ he wheezed out with his dying breath as pain finally overwhelmed him and he worldlessly collapsed to the floor."