You do understand that amount of damage is also depended on the rng and it can change, so that 500hp difference for myths does nothing for those with no defence boosts, because it’s close to (usually less) than the amount of the ±10% variance when dealing damage.
And after tests, Nyx most often would not survive Kattmander (yuck!) Darkbane even with 1k hp added, becase it deals 5200-5700 damage, while she has 4.3k hp.