This is excellent material, Rhys! I decided to use a version of it in my own Kingmaker game, with a few changes:
* I added passages to emphasize the Black Sisters more, since they're a major part in the backstory of one of my PCs. I also created an unholy symbol for their sect by mixing Gorum's and Gyronna's symbols (i.e., a sword stuck in a bloodshot cat's eye rather than a mountain).
* I wanted Armag to sound a bit more like a pillaging barbarian than a conqueror.
* I removed the references to Gozreh, who isn't relevant to my campaign.
Here's the result:
A son of Mammoths, Tiger's clan,
Armag sought the Stolen Lands,
His sword cut deep and fires burned,
And Gorum's favor Armag earned.
In victory he stoked his pride,
Across the land with blade he'd stride,
And boasting loud, with haughty eye,
Armag claimed he'd never die.
The boast drew old Pharasma's ire,
She swore to make Armag a liar,
"How dare," said she, "Armag should cry,"
"That he, mere man, will never die!"
Soon the Gray Lady's plan was sown,
To steal him to her Yard of Bone,
A dragon red, its talons rent,
'til Armag's blood at last was spent.
But the dragon has two heads, they say,
And Gorum's laugh was last that day,
The comet passed along its way,
Yet Armag's soul was here to stay.
Ovinrbaane, so named the Sword,
Was crafted by the Iron Lord,
To keep the warrior's soul interred,
Until the stars had their last word.
Women spurned by the dragon's maw,
The scapegoats of Aldori law,
Cried out when cast into the mud,
"Eye for eye and blood for blood!"
The hags sought vengeance from that day,
And Gorum's champ would light their way,
The Tiger Lord their will to bind,
Ovinrbaane they swore to find.
With Omens Lost in Stolen Land,
The blade shall never reach their hand,
'Til the tomb is found by a warrior famed,
And Armag's sword at last is claimed.
And born again, he shall return,
To widow wives, your fields to burn,
Twice-Born Armag, with damning cry,
Shall show the gods he'll never die!
Gyronna's chosen, Sisters Black,
'Neath their whip the earth shall crack,
With vile sword in the cat's eye,
Armag Twice-Born shall never die!
My plan is to reveal the text piecemeal throughout the campaign. The PCs have found passage #10 already, inscribed on the walls of the Stag Lord's Fort from when it was a Gyronnan monastery. They'll find #7 and #9 when they defeat the Gyronnan cult from RRR, and #1 and #2 on the walls of the Candlemere Tower. The full prophecy will be revealed sometime in BfB (I haven't decided exactly when).