As found on BOLS - Merry Xmas Heretics!

Drafted on 26-12-11, turns out it dates it from when you "publish" - oh well, still amusing.

As found on BOLS (http://www.belloflostsouls.net/), apparently it has been around for a few years and the author is unknown - but very clever.  Without further ado...

T'was the night before 9869986.M41, and all through the station
All there was clear, there was no abomination.


My helmet was set on the desk to my right,
On the chance that I was to need it that very night.

The guardsmen were ensconced, asleep in their beds,
All the tanks too were safe, secure in the sheds.

Marines in the barracks, some manning the wall,
Assured me the bastion never would fall.

When out in the court-yard there arose such discord
I grabbed up my bolter and unsheathed my sword.

Away to the window, I ran to take aim
As the marines around me all did the same.

My bionic eye turned the night into day
Allowed me to see, and to seek out my prey.

When what did my loyalist ocular show,
But an ancient conveyance, knee-deep in the snow.

The vehicle was pulled by horned quadrupeds
And a fiery red nimbus glowed from the sled.

The driver was mighty, his eyes full of scorn,
Dressed all in crimson like a servant of Khorne.

I gestured for others to shoot without pause,
For I was now certain this was Santa Claus.

"Fire Marines! Fire Guardsmen! Fire Ogryn and Ratlings!
Fire bolters! Fire lasguns! Fire mortars and gatlings!"

"You men there in the courtyard and you men there on the walls!
Now blast away! Blast away! Blast away all!"

But all through this maelstrom the evil one flew,
Past plasma and bolt shells and frag that we threw!

And then, to my horror, I heard on the roof
The vile cavorting of each decadent hoof.

Screaming my orders, I spun quickly around,
As down the chimney it came with a bound.

I saw its eyes glow, its vast stomach gurgle,
Bloated and fat, like a daemon of Nurgle.

Blinded by anger, I attacked with a scream -
Charged into battle with my brave Space Marines.

As we thundered towards him, closing the rift,
He reached in his satchel and pulled out a gift.

Then it tossed the vile boxes - I fell in a stoop,
As they arced through the air at me and my troop.

The wrapped missiles fell short, and plopped at our feet,
Our morale was strong, we did not retreat.

But the marines paused - our charge was disrupted,
They picked up the gifts and were quickly corrupted.

For each box contained a chaotic present -
The marines (damn their souls), found them quite pleasant.

A bolter, a flamer, a new power fist,
The Claus gave to all, and he checked off his list.

It moved through the station and left in its wake,
The sound of bright laughter and the stench of fruit cake.

The others succumbed, but it failed in its goal,
For to me it gave but a small pile of coal.

The station was lost, I could only instruct
The bastion computer to set self-destruct.

I failed to kill him, for I saw as I fled,
The target escaping, quite safe in his sled.

I heard it cry out as the base burst into light,
"Merry Christmas to all, and to all a good night!"