Death Crafter

Hi! I was looking at the Death Crafter, and I was wondering how his ability works. It states: “White Knuckles: When attacking, deal additional damage equal to 30% of artifact’s total attack bonus.”

How is this calculated? Assuming my artifact had 1000 attack, would the Death Crafter gain +300 base damage, +300 damage after all other calculations, or an additional 300% to his current damage?

Thanks!

After his damage is dealt, an additional amount of damage equal to 30% of the artifact’s attack is dealt, and that damage is completely unmitigated. So if you have 1000 attack on an artifact, it will always deal 300 extra damage.