Omega-666
From Tardis Wiki, the free Doctor Who reference
Omega-666 was a barren planet with no form of life. The air, however, appeared to be breathable.
History
The Sontaran Katsu followed a man here to what he thought was the ultimate armament. It was actually a metal flash containing the Omegan Green Plague which killed Katsu when he opened it. (DWM: The Final Quest)