So melee attacks currently have a minimum 10% damage bleed-through at max toughness and otherwise scales with your toughness %.
So at 50% toughness you take half damage
Between 90-100% toughness you take 10% damage
at no toughness you take 100% damage.
The intent here is to make toughness valuable on a granular scale - but it’s a mechanic we’re watching and collecting info on during the Beta, we’ll see where we’ll end up.