The recent favored enemy poll prompts me to remark on one frustration, which is when NPC’s and monsters play by different rules.
Certainly a good player can be aware of this and compensate, but one of those cases is in how some NPC’s can be subdued alive and others are immune. You have to metagame a bit and change up your weapon and your follower’s weapon constantly if you want any outcome but slaughter. The same applies in places like New Asagarth with the guardian wolves next to humans.
If concussion damage fell through as normal damage when the target is immune it’d be simpler.