- You may be looking for the Dalek superweapon.
The bomb's main mass, a large ring of matter-disruptors, existed in the physical universe. It extend partially into the Time Vortex, corrupting the control systems of any TARDIS it contacted. A false distress signal was created, appearing to be from a source which the pilot would want to go to as fast as possible. Just before materialisation was complete, the bomb exploded, destroying the TARDIS within the ring.
At least one reality bomb survived the elimination of its creators. It was hidden by dark matter in the Horsehead Nebula for fifty billion years. The Seventh Doctor encountered it, but since Roz Forrester and Bernice Summerfield saw different distress messages than him, he realised what was happening. He managed to prevent the total destruction of the TARDIS, but it was still severely damaged. (PROSE: Sky Pirates!)