Crivello's Cauldron

Crivello's Cauldron was an artificial, sentient sun that was also a singularity capable of scrying the future, similar to the Time Lords' Eye of Harmony.

It was created by humanity in the far future with the help of the Eighth Doctor, forming mankind's "last great hope" after the failing of the Sun. Unbeknownst to the Doctor, he had been manipulated by the last surviving Daleks, who hoped to corrupt the Cauldron into the Black Sun. The Daleks were themselves being manipulated by Rassilon and the Threshold into their own final end.

History
When the Earth's sun began to fail in the 51st century, the scientist Crivello created the Cauldron to make another one. He tried to communicate with it to give instructions, but failed and was aged sixty years as a result. He had his android Marquez throw the Eighth Doctor into the Cauldron, having realised a time traveller would not be affected as he was. The primed Cauldron departed for the Crab Nebula, where it became the centre of a new star system in an unpopulated area in that region. (COMIC: The Keep)

The Doctor and Izzy landed on Icarus Falling in the 53rd century. This was one of the six satelloids now orbiting the Cauldron. The Cauldron had generated a "communications seer", Ptolemy Muttonchops, to serve as an intermediary between it and humanity. Mutonchops was unaware of his true nature, and accessed visions of the future through the Gazing-Pool in the Cauldron's "Augury" chamber.

The Doctor and Izzy witnessed the system's invasion by the Dalek Hive, who revealed to the Doctor that they had arranged for his presence at the Keep so that he, a time sensitive, would become bonded to the Cauldron, allowing the Daleks to later use him as a conduit to control the Cauldron. They captured him and caused the collapse of the Cauldron into the "Black Sun" foreseen by Muttonchops earlier that day in the Gazing-Pool. The singularity at the heart of this black hole became a gateway into the rest of the Omniverse. The Daleks intended to sail the Hive through the gateway and make war on the Dalek Empires of all other possible universes.

However, the rift was not one directional. The vicious insectoid Daleks of another universe began to pour through the opening, alongside Great Vampires, overwhelming the Hive's forces. In the chaos, the Doctor got Muttonchops to make the Cauldron's sun go supernova, destroying all the Daleks. This left Muttonchops, devolving into a being of pure energy, and the fragment of the Sun within the Doctor, as the last remains of Crivello's Cauldron. The Doctor allowed Muttonchops to briefly merge with him, drawing out the essence fo the Cauldron still present in the Doctor, before leaving him again and exploding outwards to become a new Crivello's Cauldron, purged of the Daleks' influence.

Unbeknownst to the Daleks, the entire chain of events had been masterminded by Rassilon and carried out by an agent of the Threshold in deep cover on Icarus Falling, Sister Chastity, as a means of wiping out the Daleks once and for all. (COMIC: Fire and Brimstone)