[quote=@TheUnknowable]
<Snipped quote by Gisk>

does it deduct from the total damage?  
[/quote]

If I understand you correctly, yes. 

So if it's you:14 me:18 you'll deal one. 

Actually, as I type this out I think it'll slow battles too much. We'll institute a threshold, but it won't deduct. So in the example above, if I rolled 17 I'd do no damage, but if I rolled 18 I'd do four. 

Which do you think work better?