Tissue Compression Eliminator

The Tissue Compression Eliminator (or TCE) was a trademark weapon of the Master, especially so following his assumption of the appearance of the Trakenite Tremas. (DW: The Keeper of Traken)

As its name suggested, the TCE killed by drastically compressing the bodies of its targets to the point where life functions ceased. The Master liked to leave the shrunken doll-like corpses of his victims as a calling-card for the Doctor to discover.

The Master materialised his TARDIS within UNIT HQ and attacked the Third Doctor. In the brawl, the Doctor took the TCE and the Master fled. The Third Doctor then threatened the Eighth Doctor with the TCE, hoping that he would hand over the TARDIS. Ultimately, he decided against it and handed the device to his future self. (EDA: The Eight Doctors)

The Master later attempted to improve the design of his weapon, but a laboratory accident resulted in both him and the aforementioned laboratory being reduced in size instead. This process did not appear to physically harm him. (DW: Planet of Fire)

The upgrade to the TCE later seemed to be perfected as on subsequent appearances targets appeared to be utterly disintegrated rather than simply killed and reduced in size.

The only known entity to survive a direct hit from the TCE unaffected was the Valeyard. Multiple shots from the weapon appeared to glance off him. The Master's attack on him took place in the Matrix and it is unknown whether the Valeyard's immunity was due to the unusual properties of the environment (over which he had a considerable degree of control) or his own unique status as a projection of a possible alternate timeline.

There are a number of reported instances of the TCE being used to shrink a target without killing them outright. Most notably, Izzy Sinclair was shrunk after being shot with a TCE by the Master's disciple Sato Katsura, presumably to make her easier to keep prisoner. She was later able to use the weapon to reverse the process. (DWM: The Glorious Dead)

On another occasion the Master used the TCE against a velociraptor revived by the fountain of youth. However, it landed right back in the fountain, re-emerging unharmed but miniscule in size, and made quite a comical sight. (ST: A Town Called Eternity)

The TCE, despite its name, was equally capable of shrinking inorganic tissue: victims' clothes were also shrunk, and on one occasion the Master demonstrated the weapon by shrinking unoccupied space-suits. (DW: Planet of Fire)

The Doctor once described the method by which the Master killed as Matter Compression, which seems slightly more accurate. (DW: The Deadly Assassin)

With the help of Drax and K9, the Doctor was once able to construct a device that functioned analogously to the TCE (although this weapon shrank without killing). This may suggest that the TCE's principles of operation were based on standard Time Lord dimensional engineering rather than unique research done by the Master. (DW: The Armageddon Factor)

List of people killed by the TCE

 * Goodge (DW: Terror of the Autons)
 * Runcible's assistant (DW: The Deadly Assassin)
 * Commander Hilred (DW: The Deadly Assassin)
 * Jack Harris (EDA: The Eight Doctors)
 * Unidentified Earth police constable (DW: Logopolis)
 * Aunt Vanessa (DW: Logopolis)
 * Various Logopolitans (DW: Logopolis)
 * Various Xeraphin (DW: Time-Flight)
 * Kamelion (used by the Fifth Doctor in this instance) (DW: Planet of Fire)
 * Unidentified Earth miner (DW: The Mark of the Rani)
 * Unidentified Earth miner's dog (DW: The Mark of the Rani)
 * Duncan, MI6 agent (DWM: The Fallen)
 * Security guard Arnold Booth (BFA: Dust Breeding)
 * Mr Klemp (BFA: Dust Breeding)

Other uses

 * The Doctor was able to use the TCE to sabotage the Master's TARDIS. (DW: The King's Demons)
 * The Master shrank himself with it accidentally. (DW: Planet of Fire)
 * Used against the Valeyard in the Matrix, without effect. (DW: The Ultimate Foe)
 * Used to shrink Izzy Sinclair (used by Sato Katsura in this instance)
 * During his first encounter with the artificially-enlarged mechanoid freelance peacekeeping agent Death's Head, the Doctor was forced to use a TCE (which he just happened to have about his person) to defend himself against the mercenary. Death's Head was not injured but did find himself returned to his original size (that of a normal humanoid), which he remained for the rest of his career. (DWM: The Crossroads of Time)