I think maybe the demon slayer should have a chance to be born with a trait and demons have a chance to get a trait when they transform
A slayer trait could be iron lungs giving the users a 20% increase to Their characters lung capacity
Or like muchirichi blood or however you spell it you could make it were the player becomes shrouded for demons not strong enough to resist so it's harder to hit them
Examples of a demon's trait maybe one has poision blood where everytime there hit there's a chance to poison the person hitting them also
Another one could be adaption where the demon is able to adapt better allowing them to take less damage from poisons and weak ones aren't effective at all
Or you could just rip them off from the show if you all wanted to do something like this.
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