Spiked Sphere

The mysterious Spiked Sphere or Teleport Train is the key to killing Shub-Niggurath in the final level of Quake, Shub-Niggurath's Pit. It will fly around the area surrounding the pit and will intermittently fly through Shub-Niggurath herself. For reasons unknown the Teleporter at the end of the path surrounding the pit will send the player directly to the Spiked Sphere's current location, which is often above the Lava. If the Teleporter is used while the Spiked Sphere is inside Shub-Niggurath, the creature is Telefragged and the game is won.

Trivia

 * In Quake Champions Ranger's "Dire Orb" is inferred to be the Spiked Sphere, just with an updated look.