Last Stand Rune
I think it would be really cool if Last Stand worked on champions and monsters.
This would be a really nice rune for junglers that struggle a little early on.
When you're level 3 and you're down to 20% health, that extra 11% damage to monsters would be a life saver.
After your first, and maybe your second clear, you're probably not even going to be losing that much health from clearing so it wouldn't make that much of a difference otherwise.