Demonsbane, based on the Heralds of Valdemar series by Mercedes Lackey and sung by Heather Alexander. If you haven't read it, I highly recommend it.
Lyrics:
Along a road in Hardorn, the place called Stony Tor
A fearful band of farmers flees Karsite Border war.
A frightened band of farmers, their children, and their wives,
Seek refuge from a tyrant, who wants more than just their lives.
Now up rides Herald Vanyel. "Why then such haste?" says he.
"Now who is it pursuing, whose anger do you flee?
You are all of Hardorn, why seek you Valdemar?
Is Festil no protection? Nor bide all his men too far?"
"Oh, Vanyel, Herald Vanyel, we flee now for our lives,
Lord Nedran would enslave us, our children and our wives-
He'd give our souls to demons, our bodies, to his men.
King Festil has not heeded, or he happens not to ken."
Now up speaks Herald Vanyel. "The Border is not far-
But you are all of Hardorn, and not of Valdemar,
You are not Randale's people-can call not on his throne-
But dammed if I will see you left so helpless on your own!"
So forth goes Herald Vanyel, and onward does he ride,
On Stony Tor he waits then, Yfandes at his side.
With Nedran's men approaching, he calls out from on high,
"You shall not pass, Lord Nedran! Nay I shall not let you by!"
Now only Herald Vanyel stands blocking Nedran's way
"Now who are you, fool nothing, that dares to tell me nay?"
Now up speaks Vanyel his voice like brittle glass;
"The Herald-Mage called Vanyel-and 'tis I you shall not pass!"
Now there stand great Lord Nedran, behind him forty men,
With wizard there beside him he pales, and speaks again-
"So you are Herald Vanyel-this place is not your land.
So heed me, Herald Vanyel; and now turn aside your hand."
"Let be; I'll give you silver, and I shall give you gold,
And I shall give you jewels fair that sparkle bright and bold,
And I shall give you pearls, all the treasures of the sea,
If you will step aside here, leaving these poor fools to me."
"What need have I of silver with sweet Yfandes here?
And all the gold I cherish is sunlight bright and clear.
The only jewel I treasure's a bright and shining star,
And I protect the all helpless not just those of Valdemar."
"Now I shall give you beauty, women slaves and men,
And I shall give you power, you'll never see again,
And I shall give you mansions and I shall give you land,
If you will turn aside this day, aside and hold your hand."
"Now beauty held in bondage is beauty that is lost.
And land and mansions blood-bought come too high the cost.
The power I have already-all power is a jade-
So turn you back, Lord Nedran if of me you are afraid!"
Lord Nedran backs his stallion, the wizard he comes nigh,
"Prepare yourself, bold Vanyel, for you shall surely die!"
The wizard calls his demons, the demons he commands,
And Vanyel, Herald Vanyel, only raises empty hands.
The wizard calls his demons, the sky above turns black.
The demons strike at Vanyel, he stands and holds them back.
The demons strike at Vanyel, they strike and hurt him sore,
But Vanyel stands defiant, only to raise his hands once more.
The sky itself descending now, upon bare Stony Tor
It hides the awful battle. The watchers see no more.
The wizard shouts in triumph-too soon he vents his mirth.
For Vanyel calls the lightning down, and smites him to the earth!
The clouds of black have lifted; and there on barren ground
Stands Vanyel hurt, yet victor, the demons tied and bound.
He looks down on Lord Nedran; his eyes grow cold and bleak-
"Now I shall give you, Nedran, all the power that you seek-"
Now Vanyel frees the demons, and Nedran screams with fear,
He sets them on the Karsites, who first had brought them here.
He sets them on the Karsites, and on the Karsite land.
They look down on Lord Nedran. And they do not stay their hand.
Now Vanyel calls the farmers. "Go tell you near and far,
How thus are serves the tyrants who would take Valdemar.
I am the bane of demons, their query I defend.
Thus Heralds serve a foeman and thus Heralds save a friend!"