Originally Posted by RBmaster9345
Yeah I figured as much and I saw it right after posting this too. Might need to update my "never again" chievo
Originally Posted by Son of Kyuss
Both players, if you're playing co-op, can't die at all or neither of you will get the achievement.
Now the reason why 343i made it like this was probably because they wanted it to be an actual challenge rather than have people piggyback in co-op to unlock it.
This is definitely NOT true as far as ONLINE co-op is concerned.
I can confirm that it is possible for one of the co-op partners to die, and still the other one will get the achievement.
So one partner can stay behind, while the other partner clears the path. With online co-op over XBOXLive, this achievement is pretty easy.