Time Spiral
From Tardis Wiki, the free Doctor Who reference
The Time Spiral is a mysterious phenomenon located in the Time Vortex. The Time Spiral is located somewhere near the end of the Humanian Era, which is the probable reason why Time Lords can't go past that period in time.
This Time Spiral can rip apart a TARDIS and anyone inside if it comes too close. Because of this, all TARDIS have a device to materialize in case it does come too close to the Time Spiral. Unfortunately, the Doctor removed his emergency materialization device at some point.
The Fourth Doctor, Romana and K-9 were nearly destroyed by the Time Spiral in The Well-Mannered War.
