Opening scene for season eight, folks. This wouldn't goe away. So I wrote. Damn cliffhangers for season eight, so I just went ahead and wrote.

Opening

If one were above it all, they would see black. They would see the snow swirling and tumbling through the coal-black sky, thundering to join that avalanche of ice and stone below. They would see the clouds, from horizon to horizon. They would feel the dread, coiling in their chest before tearing through them with visceral fury.
Marching through, on line after line after line, came the dead. First the walkers, on their pale dead mounts, sat astride their skeletal horrors, etherial armour glinting with moonlight and starshadow, blades seeming to sizzle with crackling ice as they reaved a skein through the darkness.
Then came the whites. Guts hanging in rotted, putrid coils, flesh hacked away, heads and limbs missing or bent and broken beyond recognission. An endless procession, marching step after step after step over the ice and stone, as if they were as disciplined as any army to the south. For they did not screech, did not snarl. Not a sound escaped, as the blizzard howled above, as the plod-crunch-plod of their march announced the coming storm of dead fury.
If one were to see from above - but no, friends! That would present the wrong view...
The Night's King, sat astride that great monolith, as it swept a pass over the line of that marching dead, the blue eyes shining horrific in the black. No sound. No roar. Only the screaming, howling wind, as the undead dragon's wings pounded the air aside in its thundering pass.
Last in the line, the wight giant, towering twenty feet high.
On it came, that floodtide of death.
And onward Barik and Tormund ran, through the swirling snow, plodding through the snow back, back to Castle black - where the last of the Night's Watch defense held.

"Torches! Barols of oil! Swords and shields! Swords and shields! Bows and arrows! FIRE! FIRE!"
One mercifully clear-headed nine hundred and ninety-ninth Lord Commander had arrayed a paltry defense of thirty men. Still, it had to hold - it had to hold. As the men came forward with burning torches, barols of oil, and others bristled with swords, shields, bows notched with arrows, the dead came marching on, inexorable as inevitability.
"Draw! LOOSE!"
Fire arrows pelted down from the battlements, fell like rain to thud down wights in the line below.
Still, more wights swung into the battlements from below. Swords, axes, maces. Even snarling jaws and clawed hands, tearing and ripping and wrenching. Bringing the entire battlement crashing down.
With every man still upon it.
As they came from on high, they swung their swords down, flinging their shields below in front of them. Driving into the ranks from above, swords point-first.
Others clutched their burning torches, swinging them like clubs into the undead ranks as they came plunging down.
A last, paltry defense.
Swords burst through flesh, torches lit the dead on fire, flesh peeling and melting away. Swords chopped and hacked, chopped and hacked. Arms and legs flew in queerly bloodless arcs, heads caved and bellies tore open.
And it made absolutely no difference.
The men were swarmed, the dead hording them in ravaging rage, splashily devouring their flesh, ripping away their intestines, tearing out eyes and ripping them open from the inside out.
White walker blades flashed down, chopping through whoever was left, etherial blades singing a savage, keening song as they tore through heads and chests.
Battle turned from contest to slaughter in less than an instant.
The undead giant turned slowly to the section of the Wall inbetween Castle Black and the breech at Eastwatch, lumbering with great thundering strides to that towering monolith of ice and stone. Swung massive, boulder-sized fists. Pounded and pounded on that ice and stone, bringing it down, crashing and splintering in icy heaps.
And from the lengthened breech, another cloud approached. More of the army boiled to the breech, poured over and in, now coming from both the wasteland of Eastwatch and the further cavity smashed into being by the undead giant.
And of the Night's Watch, nothing remained.