Planet (Meet Doom - the Universe's Greatest Assassin!)

A planet seemingly within the Time Vortex was the location where Doom, (GAME: AI am the Doctor) an assassin for the Lesser Order of Oberon, (WC: Meet Doom - the Universe's Greatest Assassin!, etc.) was sent between missions. (GAME: AI am the Doctor) Doom seemingly created a series of "mission updates" here, (WC: Mission update from Doom!) reflecting on her remaining time. (WC: The universe's greatest assassin has just 24 hours to escape Death and find the Doctor - where will Doom's Day take her next?, Mission update from Doom!, etc.)

History
After finding that she had 24 hours left to live, and deciding to take a mission at the Stormcage Containment Facility, (PROSE: Hour One) she was briefly sent to this planet in the Time Vortex, and reflected on her remaining 24 hours, and that she needed to find the Doctor, (WC: Meet Doom - the Universe's Greatest Assassin!) seemingly as part of a series of "mission updates", (WC: Mission update from Doom!) before being sent to the facility and sorting out her target there. After doing this and getting some advice from River Song, she set off, taking the mission on New Calamino at the waxworks museum, (COMIC: Target Selected) and briefly appearing again on the planet, reflecting that she now had 23 hours to go, and inviting someone to join her on her journey. (WC: The universe's greatest assassin has just 24 hours to escape Death and find the Doctor - where will Doom's Day take her next?) She proceeded to appear at the museum, meeting the wrong Doctor and completing her mission. (COMIC: The Plastic Population)

After a mission in New York, 1883, (COMIC: A Doctor in the House?) Doom again visited this planet, where she reflected on her remaining 19 hours, and the various creatures she had encountered, with her vortex manipulator displaying a holographic 2D depiction of a skull. (WC: Mission update from Doom!) After another mission, this time on a dead planet, (COMIC: A Doctor in the House?) Doom found herself here again, beginning to reflect on her remaining 15 hours, before being distracted by her vortex manipulator's 3D hologram of K9, with her remarking "is that a robot dog?!". (WC: 15 hours left to find the Doctor, and Doom receives an unexpected communication - from a very good boy!) This turned out to be an ad placed by K9, requesting help against attacking pirates on Cal-Q-L0n.

After Doom sorted this out, and left Kamelion and K9, she again found herself on this planet. She reflected that she was running out of time, and not getting any closer, hoping that she'd find the Doctor sooner or later. A voice from her vortex manipulator informed her that her next mission had been selected, and she left. (GAME: AI am the Doctor)