Warhammer 40,000: Space Marine

Another good place to do this is during chapter 12 when you are fighting the Warboss this is the last part of chapter 12 if you're using mission select. Part way through battle the Warboss breaks a hole in the wall and Orks come spilling out. Right when this happens put 5 launcher rounds right in front of this hole (I put them in a semicircle in front of the hole) and right when they jump out hold right bumper to detonate them. If you mess up restart checkpoint and you will be standing right in front of the hole in the wall or you can wait and he will break another hole in the wall. The main reason I did it here was because you have no other marines with you. I was having trouble with the computers shooting the Orks when I am trying to set up my launcher rounds.

Chain of Death - 10g
Multi-kill -- Detonate a chain of 5 consecutive Vengeance Launcher rounds, killing 10 enemies.

The Vengeance Launcher is unlocked relatively early in Ch. 1. The gun basically fires bombs/grenades to which you control the detonation. You have the ability to put out more than 5 rounds at once, but going beyond 5 will cause you to lose your first rounds (i.e. Round 6 detonates Round 1, Round 7 detonates Round 2, etc.)

How to Detonate a Chain - To detonate a Launcher round in general, you merely tap the RB and it will explode. However, to detonate a chain you must hold down the RB until all 5 Rounds have exploded. Repeatedly hitting the RB and making them explode separately will not work for the achievement.

To get this achievement, you want to wait until you have a large group of Orks coming towards you. I got this achievement where the Imperial Guard come up on the lift to get you, right where you find the Power Axe. You have some time to setup before the Orks begin attacking. I drew a straight line with my rounds, and stood back towards the lift behind a wall until the Orks came close enough to the rounds. If you find another place to do it, GREAT! This is just where I recommend doing it. Two notes though:

1. The Orks will come in multiple waves. The first wave should have enough to get 10 kills (I didn't count how many actually came), but the second wave comes quickly after the first one. I waited until the second wave came, giving me more Orks on screen, and having a better chance of killing 10.
2. The Orks may swarm one of the two other Ultramarines with you. If they do, that's fine. Simply come out from behind the cover and shoot at them once or twice with your Bolter or even walk up and hit them in Melee. This will cause them to pursue you. Then run them back towards your charges. When they're in place, blow the charges and your achievement will pop.

If you don't get the achievement on your first try, simply hit pause your game and choose Reload Checkpoint. This will take you back to before the battle begins, and you will once again have time to set up. I also used this location to get the following achievements:



Good luck and happy hunting! If you're going to vote negative let me know why!

another easy solution for me, i've done this in chapter 3 in the last part (where you also could do "The Emperor's Marksman" achievement.

it's almost the same, put 5 launcher rounds in front where the horde is coming from, wait a moment, till are there enough, than hold the RB button, and BOOM there it is