The Doom Chief Set is a boss drop from Marua, The Shadow that has the same Level requirement but has higher stats than the Iron Set.
“The cloak of the corrupted chief of Doom Island, Marua”
“The headdress of the chief of Doom Island.”
As a vanity, the Helm has the same appearance as the Valkyrie Helmet, but with a black and purple color scheme. While the cloak looks similar to a regular vanity shirt, but with a unique design.