During the first awakening of the Eldrazi on the planes, the angels managed not to be subdued by the Eldrazi, but the interplanar monstrosities still left their mark on the angels. This caused the Zendikari angels to wear their halo down over their eyes, symbolizing their blindness to the Eldrazi's atrocities and their powerlessness to aid. The halo stings when worn this way and the angels can see only glaring whiteness. The halo serves as a shameful kind of leash, shackling the angels to acquiescence and preventing them from interfering with the destructive progress of the Eldrazi. During the millennia, this inability to help was misinterpreted as a sign of equity and impartiality.
The memory of the Eldrazi's destructiveness and the angels' responsibility to Zendikar, however, survived inside a few select angels, the greater archangels. They were powerful enough to resist the Eldrazi's reign, maintaining their sight, their loyalty to the downtrodden and their ability for voluntary action. Among them was Iona. She defended Zendikar during the last awakening of the Eldrazi, but even her legacy had become tainted by their power. Her formidable power could do nothing to fend off the colorless magic of the Eldrazi titans. The epithet given to her by her adherents, the "Shield of Emeria," tied her to a distorted vision of Emrakul. Everything she had done to fight the Eldrazi had ironically served as a tool for their cause.
When Iona descended from Emeria to battle the Eldrazi, she left the Sky Ruin unguarded. It is unknown the precise role she assumed during the battle between the Eldrazi titans and the Gatewatch, and even if she survived the ordeal.
Iona, Shield of Emeria art from Zendikar. Art by Jason Chan.
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