I've got a lot of multi-kills in Multi-Team.
In King of the Hill on Multi-team, don't always go for the hill. Since everyone will be going for it, you could chuck a grenade in there, or just shoot everyone while they're in it.
But... idk. Multi-Team is a wild playlist. It's guarenteed <-(Wrong spelling?) that you will get a lot of double kills and stuff.
(You should also try infection.)