[PASSIVE] Unrelenting Killer

When a heavy hit lands (30 damage or more), a blow of 15 or more from someone using their ultimate, or a stun (even while held), you go down instead: that hit is ignored, the stun is shaken off, and you take no damage at all for a few seconds. The ground shakes around you as you fall. Then you sit back up and recover some health. Has a long cooldown.