Hunt for the Doctor

The assassin Doom of the Lesser Order of Oberon launched a hunt for the Doctor across time and space in order to escape her fate: an enemy of Doom had sent "literal Death" to hunt her down. Doom had only twenty four hours to find the Doctor. (WC: Meet Doom - the Universe's Greatest Assassin!)

Marked by Death
To be added

Encounter with Kamelion
At one point, Doom crossed paths with K9 and who she believed to be the Thirteenth Doctor, only to learn it was Kamelion in disguise. Doom also realised the Thirteenth Doctor was likely not the incarnation she needed. The two robots promised to tell the Doctor about Doom's search should they cross paths with the Doctor again. (GAME: Lost in Time)