The TARDIS is a time and space machine Vahl owns. She is also very bad at piloting it. Jordan also used the TARDIS to cheat the game and get inside The College Of Winterhold.
It has multiple Console rooms, but Vahl likes the original, it can travel to Standing Stones, Words of Power, Hold Capitals, and a custom loctation, which orginally was outside Vahl's home on Solstheim, then was moved outside Fort Dawnguard, then finally got moved to outside Vahl's current house in Windhelm.It was originally owned by Jordan's old character Trinity, though, either by design or chance, was sent into Vahl's timeline and came into her possession.
It has had many companions, Vahl's companions being most, but has also had an Argonian and a Khajitt, that Jordan named Amy and Rory.
Vahl's Fallout successor Cywren Caster and Garry's Mod character Papa Acachalla Also own TARDISes, but Vahl's appears to be less advanced than the counter parts. Ironically however, despite Vahl's fantasy like reality her TARDIS is the most useful of the three. As she can call it to her whim with magic and it is the easiest to control.