Bubble universe rift

A bubble universe rift was a time rift which served as a gateway to a bubble universe.

It was through such a rift that House lured Time Lords into his bubble universe, allowing House to consume their TARDISes and harvest the Time Lords' bodies for "spare parts" with which to increase the longevity of his pets Uncle and Auntie. (TV: The Doctor's Wife)

To pilot her TARDIS into Gallifrey's "little bubble universe" (where it was once again hiding by the time discovered the secret of the Timeless Child and decided to slaughter the Gallifreyan people), the Thirteenth Doctor flew her ship into a firey-red rift in the wall of the Time Vortex. (TV: Spyfall)

Behind the scenes

 * During the scene in TV: The Pilot in which the TARDIS travels to the Dalek-Movellan war zone, this short scene in which the TARDIS leaves through the rift for the House planetoid is re-used.