Sudden Damage

Since the launch of 6.4 I have been noticing a sudden and large application of damage happen after some fights. Played in a custom against a friend who was playing rumble. after a skirmish I suddenly took a massive burst of damage and died. He did not build Duskblade of Drakthar. I have noticed it happening in most games played since 6.4. Perhaps im missing something. Could I get verification form a second source? Perhaps ask for some extra attention to be payed?