[PASSIVE] Regenerative Healing Factor

Adamantium is only half of what makes you hard to kill. When a fight takes you to the brink, your healing factor takes over on its own: torn flesh knits back together, and whatever was poisoning, burning or slowing you simply burns out of your system.

While the factor is working you also shrug off a quarter of all incoming damage. It cannot be triggered on demand and it needs a long time to recover afterwards, so it saves you once per fight, not once per exchange.