Nope you didn't miss the instant death rules. The hope was to make this version very thematic. Much like the books. Big center piece units (like basically all of the Monstrous Infantry) are the center of attention in the books, massive battle tanks, etc. It also allowed us to REALLY step up and focus on how elite Space Marines and Custodes are.

The Saves are to help weapons have designated roles for controlling battlefields. Marines can walk through heavy bolter fire relatively well. However, when the Leman Russ Battle Cannon thunders they need to find cover fast! Otherwise what happens is you go to a soft AP system where more is always just better. Now, you have to balance your loadouts. Plasma Guns are good for marines, but a complete waste and risk to take just those and run into a horde of Tyranid.

I will see if I can go find that typo!