I'm now a "veteran" GM of one Deathwatch game, we managed to play about a good third of the Final Sanction adventure today, and i just got to say that the marines ability to shake off ridiculous amounts of damage was insane...(although my crappy dicerolls didn't help one bit)
Okay the rebel hordes in the adventure are not really meant as a serious threat but still my kill-team (Devastator marine, Assault marine, Librarian and an Apothecary) managed to rout size 50 hordes in one round of combat easily... (Hmmm... I might need to put some orc hordes into the mix)
Psychic powers seem to be really devastating to hordes, at least the Avenger power which turns the Librarian into a walking heavy flamer which gives 1d5 + range/3 magnitude damage plus the extra 1d10 since it's an area effect psychic power. (If I'm interpreting the rules correctly)
So the question
to all you veteran DW GMs, and the reason for this post, is how have you managed to kill a marine or marines in your games? Of course players can also tell their great stories of valour and death...
(I got really close with the help of six genestealers and a few lucky dicerolls...)