Tethering device

The tethering device is a UAC technology which occurs in Doom (2016). It is a form of interdimensional tracking and transport device which allows humans, demons, and objects tagged with one to be retrieved from Hell remotely, without use of a pre-existing portal between the dimensions. Tethering devices were used extensively in the research and exploration of Hell by the UAC Mars Base staff in a series of expeditions beginning in 2145 dubbed the "Tethering Operations," leading to recovery of a multitude of artifacts such as the Helix Stone, an ancient demonic tablet which contained encoded information about Argent energy, as well as the location and fate of the Doom Slayer.

Despite the capability of using a tethering device to retrieve humans, it was apparently considered too expensive or otherwise unnecessary in the majority if not all of cases, and in many expeditions, especially those launched under the command of the fanatical Olivia Pierce, the UAC operatives willingly laid down their lives to the demons after accomplishing the tagging of their targeted objects. This leads Dr. Samuel Hayden to refer to the Doom Slayer as "the only flesh and blood to walk between dimensions."

Tethering of the Slayer
During his visit to the Advanced Research Complex to visit Samuel Hayden in person, the Doom marine experiences an electrical surge while trying to activate the door panel leading to Hayden's office. Having no apparent ill effects after it dissipates, the door immediately opens and Hayden begs the marine's pardon for the "forced upgrade," and explains that he has installed a tethering device into the Praetor suit without permission, as he did not believe such permission would be granted but that it would become a necessity in the quest to stop Olivia.

The tethering device is engaged remotely by Hayden after the marine obtains the Crucible, returning him to the VEGA Central Processing facility, and again at the end of the game after he defeats the Spider Mastermind. In this final occurrence, Hayden abuses the tethering device to hold the marine hostage while he steals the Crucible from him, and then re-engages the device to send the marine to an unknown location as the game reaches its conclusion.