you have been combat before where someone is trying to kill you and they leave the game or warp

how about it that if they:

Leave during combat: they instant die

warp: prevented from warping

Look at this from a developers point of view. Now how would this work?

If damage has been taken with in 3 seconds of ever of these commands such happens

Actually good idea. And if damage has been delt

youll have to use a andif command i believe for that