Help me find the name of this

CripticCorp · December 2016

So I came across this guy wearing this the other day, I did not get a chance to ask him before he warped away but I did take a screenshot.

Pretty sure it is not a costume, so that leaves monster sets.
Any help would be appreciated.

Yuls · December 2016

Infernal Guardian

Dubhliam · December 2016

Infernal Guardian

You need to do Undaunted pledges to get Undanted Keys.
The shoulders have a chance to drop in the Glirion's chest.
The Helmet you get from the last boss in veteran City of Ash 1.

CripticCorp · December 2016

Thanks everybody, Anyone know if there is a "Green" Glowy Glowy Version of it??

Dedimos · December 2016

Only red

CripticCorp · December 2016

Thanks again