|Sources||Enter the Eldrazi, Part 3|
Ugin was one of a trio of planeswalkers — a group that included Sorin Markov and the Lithomancer — that lured the Eldrazi to Zendikar to imprison them within the Eye of Ugin. Ugin's part in sealing them was to combat the colorless Eldrazi with his own colorless magic as well as providing the magical key to unlocking the Eye. He arranged the hedrons to direct leylines of energy, which helped contain the Eldrazi and were not to be disrupted.
In "Enter the Eldrazi" Nicol Bolas informs Sarkhan Vol that he had battled Ugin thousands of years ago (it is later revealed to have taken place on Tarkir) and killed the other dragon. He claims to have dug deep into Ugin's mind for information about the Eldrazi and their prison. In spite of this mental violation, Ugin was apparently able to withhold certain information about the full extent required to release the Eldrazi.
Sarkhan is plagued by whispers in his head, which might originate from Ugin. 
Breath of Ugin
Ugin was first mentioned on the futureshifted card Ghostfire. Matt Cavotta wrote a short story entitled "How Many Eyes?" inspired by this card, in which Ugin emerges from a time rift, implying this character's alternate reality origin. It is not known if it was the same character who was involved in the Eldrazi plot.
The breath of Ugin, also known as the ghostfire, is an invisible colorless flame. It was used by Ugin against the Eldrazi and, along with the presence of three planeswalkers, it is the key to activating the Eye of Ugin.
Eye of UginEye of Ugin is a secret underground cavern in Zendikar. Here the spell that kept the Eldrazi imprisoned was focused.
At some point, Nicol Bolas became aware of the Eye and later sent Sarkhan Vol to guard it. Chandra Nalaar discovered this place by following a map she first found on Kephalai, with Jace Beleren chasing after her.
When Chandra and Jace confronted Sarkhan at the Eye, they found out that colored magic was absorbed immediately, taking no effect. Moreover, the place was keyed to a specific event, the presence of three planeswalkers and the breath of Ugin. During their fight, Chandra used an invisible flame spell against Sarkhan, thus triggering the release of the Eldrazi.
- Doug Beyer. (March 17, 2010.) "Gods and Monsters", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Doug Beyer. (March 29, 2010.) "The Eldrazi Arisen", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Matt Cavotta. (May 17, 2007.) "How Many Eyes?", Daily MTG, magicthegathering.com, Wizards of the Coast.