So one of the players had divine retribution on him, and essentially became the Mage Suicide Bomb (long story).
However, at one point, an ogre with knockback attacked him, and did enough damage to kill him. Normally, this would pop DR and kill him. However, the character gets knocked back as well. The question then becomes, does knockback take effect before or after damage is applied? In this case, it is important. If it blows the guy out of range of DR, then the monster survives the divine retribution. Otherwise, he gets killed with the mage bomb.
I "ruled", and it was generally agreed, that knockback takes effect even if armor soaks up all the damage, so knockback would occur first, then the character would land, take damage, and die, blowing of Retribution.
Not that it mattered. Next turn the mage respawned, double-moved right up to the **** ogre, and the warrior ran over and cut down the mage, killing the ogre and ending the quest.
We now call the tactic Mage Bomb where you run the guy with divine retribution into the middle of a room and the warrior tools up right behind him to waste the mage, blowing DR and bringing the room down.
It sucks as OL, but I can usually set up a couple of staggered waves of cheapie enemies to make it not a good idea to try that unless the opportunity arises.