No, not that Hat Trick, this is the other one.
Bumped up from the comments in another post, here's a blindingly obvious statement by Keith Giffen. Over at ComicMix, he's asked about "Countdown", which characters he liked and didn't like.
And everyone knows I hate Karate Kid. One of the reasons I stuck with Countdown was that I'd have a chance to hurt him again!
Giffen already succeeded at killing off Karate Kid twice, the Pre-Crisis version and the SW6 version.
Countdown's version appears to be the resurrected Pre-Crisis (Lightning Saga) guy - I'm a few weeks behind in my reading, so if there's some other explanation, please don't repeat it here - so leave it to Giffen to try to off him a third time. Three times for the same character - that's a hat trick.
I think the Karate Kid in the regular Legion series is safe for now, as he's being written by his original creator, Jim Shooter.