Not sure how this is possible?

[Demon hunter]

My last line of battle

Snow Leopard has been defeated!
You recieve 5298 experience as Snow Leopard dies
You have gained 1g 39s for defeating Snow Leopard
Snow Leopard takes no damage due to deflecting all 0 points of Adam Dubay the Demon Hunter's attack
Adam Dubay the Demon Hunter fumbles his attack!
Adam Dubay the Demon Hunter takes 24 damage and deflects 119 damage from Snow Leopard

How does he die when i fumble my attack dealing 0 dmg?

[Demon hunter]

Just happened again...

Mountain Troll has been defeated!
You recieve 5407 experience as Mountain Troll dies
You have gained 8g 6s for defeating Mountain Troll
Mountain Troll takes no damage due to deflecting all 0 points of Adam Dubay the Demon Hunter's attack
Adam Dubay the Demon Hunter fumbles his attack!
Adam Dubay the Demon Hunter takes 36 damage and deflects 116 damage from Mountain Troll

[Isoyami]

If I remember, vaguely, Ben said it happens when you kill a creature by "The Evil Stare".

I think you should be more worried that you are fumbling so often instead!