The Three

The Three was a group of planeswalkers allied together to imprison the Eldrazi in a plane.

Ugin was the mastermind of the trio. They decided to force the Eldrazi titans into physical form and trap them on a plane, sacrificing that plane for the well-being of the Multiverse. They searched for a plane with lush ecosystems and uniquely dynamic mana, a powerful lure for the Eldrazi's insatiable hunger. They finally managed to imprison the Eldrazi on Nahiri's own Zendikar, in the mountains of Akoum.

The Three agreed that if the results of their ritual were ever disturbed, all three would return to Zendikar, and they departed. For centuries, Nahiri served as Zendikar's guardian, ensuring that the Eldrazi remained in confinement and swiftly addressing any other threats that arose.

In-game references
Referred to:
 * Ugin's Construct