Halo 3

Most probably done by luck - just kill a group of people that are all trying to kill each other - preferably on an oddball or king of the hill match because these are usually the types of games that people stay together in.

This must be earnt in a lone wolf match!

Find a level with a missile pod (say, Vahalia). Next just aim for a bunch of people trying to kill each other, and you'll get it.

This achievement can be easily won with patience and a sword. This is probably best to get on Epitaph because everyone gathers around in the middle of the map. Just wait for the 2-3 people to get into combat and Lunge(RT) at one person then Melee(B) the other person while they were lunging at your victim and with all that noise it should attract another victim to come to attack then just spam both the (B) button and (RT) in hopes to get your third (3rd) kill in a row in under four(4) seconds. This can also cause you to get the Steppin' Kill achievement and get you a piece of armor for your elite character. Hope that you like your new armor and this nifty guide. Happy Achievement Hunting

You can get it in a social free-for-all playlist along with the ranked I learned (Or at least playing the "Living Dead" weekend Playlist on "Speed Demons" on the "Living Dead" version of Valhalla). The way I got it was, there were three guys coming at me with a Warthog and I used a Gravity Hammer to destroy the Warthog. I was lucky to not get splattered the second time I tried, which happened the firs time as you can guess, the second time though they had no chance, It was like "I yall good suckers, BLAM!!" I've also learned that you can do the same with any power weapon, or a well placed grenade stick in the same situation, but how I did it was more fun. :)

You should try going for this achievement and the sword achievement at the same time. Find a map that has a sword and kill 3 enemies within 4 seconds of each kill. Close quarters will help with this and if you're lucky you might also get an Overkill which is an achievement also. Here is a video of me getting all 3 achievements at once to show you what I mean. :)