Bloodlord Mandokir - the second boss in ZG, uses a certain ability called Decapitate, killing the targeted person instantly.
To not upset the players that get killed by this, you don't lose durability when killed by him.
Matched with the guild perk, Reinforce, you actually gain durability from this encounter! Here's how it works:
The Reinforce perk does not take away 20% of the durability lost, it just gives you back 2% of your total durability for every time you die. But even when you're not losing durability, you're still getting that 2% durability back every time you die.
It's not much, but it helps
EDIT: Dying to Devastating Slam also increases your durability. Screenshots for proof at this post http://www.mmowned.com/forums/world-...ml#post2082844