Some of Doom's cosmetic items are missing backfaces.

The following items are missing backfaces
1. Crown of Hells set: Missing backfaces on the shoulders, hair and apron.
2. Eternal Fire set: Missing backfaces on the entire belt, arm guards, shoulders, and helmet.
3. Impending Transgressions set: Missing backfaces on the arm guards, and the tail.
4. Incandescent Liturgy set: Missing backfaces on the belt.
5. Incantations of Hell set: Missing backfaces on the helmet, shoulders, leg armor, and arm guards.
6. Onyx Fume set: Missing backfaces on the belt, tail, and arm guards.
7. The Apocalyptic Fire set: Missing backfaces on the belt, pauldrons, and arm guards.
8. The Burden of Eleven Curses set: Missing backfaces basically everywhere.
9. Daemon Prince of Khorne set: Missing backfaces basically everywhere.
10. Fires of Vashundol set: Missing backfaces basically everywhere.