Thû and Huan

Thus came Thû, as wolf more great

than e'er was seen from Angband's gate

to the burning south, than ever lurked

in mortal lands or murder worked.

Sudden he sprang, and Huan leaped

aside in shadow. On he swept

to Lúthien lying swooning faint.

To her drowning senses came the laint

of his foul breathing, and she stirred;

dizzily she spake a whispered word,

her mantle brushed across his face

He stumbled staggering in his pace.

Out leaped Huan. Back he sprang.

Beneath the stars there shuddering rang

the cry of hunting wolves at bay,

the tongue of hounds that fearless slay

Backward and forth they leaped and ran

feinting to flee, and round they span,

and bit and grappled, and fell and rose.

Then suddenly Huan holds and throws

his ghastly foe; his throat he rends

choking his life. Not so it ends.

From shape to shape, from wolf to worm,

from monster to his own demon form,

Thû changes, but that desperate grip

he cannot shake, nor form it slip

No wizardry, nor spell, nor dart,

no fang, nor venom, nor devil's art

could harm that hound that hart and boar

had hunted once in Valinor. 

The Geste of Beren and Lúthien
J.R.R. Tolkien
(lines 2,740 to 2,769)