The Sendings of Darkness are times in the history of Auberean involving the Shadows. Unfortunately there is not a more precise definition of what constitutes a Sending, since we only know what the third and fourth one were, and the fifth Sending which occurred as part of the Asheron's Call 2 backstory is no longer considered the future of AC1.

The Third Sending of Darkness was the Yalaini Shadow War, the war they fought against Bael'Zharon and his army of Shadows.[1] The Fourth Sending of Darkness was the Isparian Shadow War, the war Isparians fought against Bael'Zharon when he returned in Portal Year 11.[2][1] For more information, see: The Fourth Sending of Darkness. In AC2, the Fifth Sending of Darkness was the return of Bael'Zharon which culminated in the Battle of Kings.[Citation Needed]

The Fivefold Curse / The Curse of Eibhiill Heretical Prophecy

As we were sent by the Darkness
The Darkness shall send again
An avenging star
A light to bring darkness
The Darkness shall send then
A knowledge:
A power to bring destruction
For Alaidain's blood shall be
The death of the people
And then Darkness shall send yet again
And once more, and the Darkness shall win

As darkness draws about light
And all falls to ruin so shall come; the star.
The darkness will impart its wisdom,
And the Light shall lose its way.
And blackness shall fall across the land,
And the Light will be hidden above.
Then shall the light gain its wisdom
And Champion.
For Alaidain's blood shall be
The savior of the people
And then Darkness shall send again,
and be beaten
And so it will send again,
and be beaten.

Sources: Alaidain's Gem & Prophecies.

References