Disable Rush and/or skills that push the slime king.. (or just disable kb like for snowman) It was obnoxious that people kept pushing the slime away from the attackers. Notable name: Destructe.. smh
I think it's a bit more complicated than just disabling the skills. Probably have to add a boolean if(push skill used == true){ignore NPC movement packets?} Not sure if push skills apply with this logic though. ..Because in most cases the skills still work client side right? Such as teleport.
I think I've proved my suspicions. Since the skills are client sided (client sends the NPC location update..) that needs to be blocked for any recent usages of the knockback skills. It'll still appear that it was pushed on the pusher's screen but soon teleport back to its actual place. You probably know this already, sorry if you do and I'm just stating the obvious. probably complicated in the source if it doesnt have a packet filter for general edits like these..