Guild Wars 2

I’m trying to find the rest of the “Lone” set. I was at Straits of Devastation when saw it in a karma vendor. Anyone knows where I can find them?

is it just me or is it ironic that the helm that appears to be the only one of the set and the name of the item is called Lone

That mask goes by a few names, lone, mending etc.
It’s a one-off and not part of a set