Done this by accident, and was able to duplicate it again.
1. Join x-realm group.
2. DPS boss till he's low.
3. Die in the breath, release spirit and leave group.
When that group kills him, you'll get felblight and possible loot and you won't be saved.
You can repeat this multiple times, but don't make it too obvious.
I managed to do it on 2 alts so far.
FYI : If this is a repost, then kindly close the thread :P