Effect
This effect may occur once every 60 seconds.
Nerves of Steel
Nerves of Steel is a strong emergency passive against sudden death: if you would take fatal damage, your life is set to a residual value instead, and for several seconds all incoming damage drops drastically while you're immune to loss of control. The effect does carry a long internal cooldown, though.
That makes the passive a safety net that lets you survive an otherwise fatal hit and grants a short window to recover or flee. It's especially valuable in content with high burst risk, where a single blow can be lethal. Because it triggers only rarely, it's pure insurance rather than constant protection.
The 3 seconds after it triggers
When the passive fires, you sit at 15% Life, take 95% reduced damage for 3 seconds and are immune to crowd control. You have to use that window actively: Sprint or Furious Charge gets you out of the danger zone, or Ignore Pain extends your protection beyond it. If you just keep fighting without reacting to your low Life, you waste the rescue.
The passive is available from level 13 and covers the moments while leveling when you underestimate an enemy.
The minute afterward
After it triggers, the effect is unavailable for 60 seconds. During that time you have no safety net, and that is exactly when it pays to play more carefully or use defensive skills more deliberately. Ignore Pain is the active complement: it reduces damage taken on demand and also grants immunity to crowd control.
Alongside offensive passives
On the passive bar, Nerves of Steel often sits next to Rampage and Boon of Bul-Kathos. Those two focus on damage and the cooldown of Wrath of the Berserker, so Nerves of Steel is often the only safety measure in an otherwise very offensive selection.