This would be in PvE.
Say you’re running along, pass a fort, and encounter some pretty bad lag. As you round the corner of the fort, you see the owner chopping up bodies, of which there are more than 30. You think to yourself, “He’s just had a purge, that explains the lag.”
As you run by down the narrow pass, you find yourself surround by Nordheimer fighters, Bears, and Ladagara. Your only direction is back to the fort, due to it being an ‘Army of Nordheimers’ purge wave. You and your follower fight off your attackers, and you see that the base owner has been killed, along with a number of his thralls.
The thralls don’t seem to be making any headway against the bears or Ladagara, because they have truncheons, as you find out later when the base owner is upset that you killed the things that killed him and his thralls, because he didn’t need, or want, your help.
So, the question is, should you bother to help people when you find yourself in danger from their purge, or sit back and laugh as they die?