Event farms are full of people knocking and blocking the paths of mobs that try to reach the event camp at their spawn so they ruin their pathing and glitch they take no dmg and can kill them there easily. I have no problem adopting to this but..
Believe it or not this -is- an exploit using game bug to your advantage. Please ban these people and fix the pathing bugs – or – make mobs invulnerable as you did on pentient camp.
Guardians putting up a blocking line also should not be possible to even mobs.