Attacks don't interact with vanilla features
I'm not sure if it is entirely an issue, but certain features relating to damage from mob attacks do not work on mobs from this pack. Two I was able to find are resistance and thorns. When I give myself resistance 255, nothing else can damage me, but mobs from this pack can. As well, enemies that attack you physically do not take thorns damage. I am not sure if this is intended behavior. I am playing on the 1.16.5 version.