Time Spiral

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, each TARDIS has a device to materialize in case it does come too close to the Time Spiral. Unfortunately, the Doctor had removed his emergency materialization device at some point.

The Doctor, Romana and K-9 were nearly destroyed by the Time Spiral. (MA: The Well-Mannered War).