Aiur

({t}: Add {u}, {b}, or {r}.)
As Aiur enters the battlefield, you may pay 3 life. If you don't, Aiur enters the battlefield tapped.
"The Swarm brought ruin to our world. Our proud people became refugees. And yet, they could not shatter our unity, for we are bound by the Khala...
The sacred union of our every thought and emotion. Today we retake our homeworld... and with it, our legacy."