WH40k: Changeling

After a few contortions, the Changeling was the height and shape of a human. The robes of the daemon hissed as they became the uniform of a Krieg Imperial Guardsman. The Changeling slapped it's own head a few times to take on the appearence of a helmet and gasmask. After a few more adjustments, the Changeling was ready to deliver the letter that would put The Plan back in order.  The daemon stepped out of the dugout and into the trenches, un-noticed, and began to make his way to the command bunker.
The Plan, ordained by Tzeentch itself, stated that The Krieg Imperial Guard were to claim this planet from the Khorne Skull Taker Marines. And the Krieg weren't going to do that if they charged up and out of their trenches in the next hour. Thats what the original order delivered to field command said:  capture the  geothermal power site with mass infantry assault by 0300 today.  The foolish humans were going to get themselves slaughtered if they attacked.
The Changeling entered the cramped command bunker. There was five commanding officers, a pair of vox terminals, a strategic map table, and a caffiene brewer all squeezed in together. The General leading this section of the front was standing and looking over the table map, a steaming tin cup in her gloves.  The sleeves of her dark trench coat was rolled back so that it revealed her left arm had a scar running the length of it and her right arm was a robotic limb.   She had her gasmask clipped to her belt and it could be seen that she wasn't that old but her face was weathered.
"Excuse me, general, I have a message from supreme command." said the false messenger. The general looked up and stuck out her hand to recieve the sealed letter. She opened it and read the contents silently. The general gave a grumbling sigh, the Changeling grinned beneath his mask.
"Something wrong, Sir?" asked a colonel whose face bore two large scars across his face. The general shook her head and waved the letter as she addressed the men standing around her.
"I'm glad the Supreme Commander came to his senses and has cancelled the assault but that leaves us with no orders and if the field reports are correct then those heretical monsters will be on us by nightfall. We need to do something other than practise our firing line for the thousandth time, we need more support. Mister Jaeger if you could please."   
"Right, I'm firing up the vox caster" said a lieutenant who pulled a crate in front of one of the broadcasting terminals and sat on it.  
The changeling quietly excused himself from the bunker.  Although the chaos space marines lacked the technology to decrypt the vox broadcast, they were still capable of triangulating the source.  By contacting Supreme Command Headquarters, the General had served the plans of Tzeentch threefold: She would provide a lure that would drive the idiotic servants of Khorne into the firing line of the Krieg guns.  She was going against orders for zero vox communication, thus leading either to demotion or decreased trust in her, a condition that could easily be exploited. Finally, the original order that would bring the entire planet under the power of the Blood God would be negated and replaced with a defensive strategem that would ultimately bring down the chaos space marines.
Things were going exactly as planned.