Unfortunately for Madara, his crew, and all of existence; Madara, in his ignorance of what exactly a demon was, hadn't taken into account what a technique to convert all energy into force would do. The desperate demon -using what little intelligence and survival instinct it had- had attempted to flee into the warp, a dimension made entirely of energy.
Madara's untested technique performed absolutely perfectly, converting all of the targets energy into kinetic force in an instant. Unfortunately the technique wasn't able to differentiate the energy of one particular demon from the energy of the Warp itself, nor any of its denizens.
The conversion took centuries, slowed by the desperate deities of all creeds futile attempts to halt the inexorable march uniformity and true, final death. At first the Lord of Change supported this unprecedented attack, seeing only the transformation it brought; once he saw the total, unchanging nonexistence it left in its wake he became the most desperate to stop it. In the end the Fate Weaver learned what it truly was to lose hope as all his plans crumbled to ash in his desperate hands; he met his fate broken and defeated, a mirthless chuckle his final words.
At roughly the same time the Deceiver's opinion changed, so to did his rival. For what Tzeentch saw beyond the conversion was exactly what the Lord of Stagnation wanted; a completely unchanging universe. The Lord of Decay laughed joyously as the blank wave of unmaking swept over his kingdom and himself; embracing the end of everything with open arms.
Khorne was of much the same mind as Gorkamorka, and simply fought against the change just to fight one last time. In his fiery thoughts a hopeless battle was just as good, if not better, than any other. The two deities of such similar minds fought together against the wave of force… and met their ends with smiles on their lips and laughter on their tongues.
Slaanesh met the encroaching wave the same way she met every thing; more drugs. The god of over indulgence went out with the greatest party ever thrown. The sheer mind boggling amount of sex, drugs, and rock and roll enough to shatter the minds of the most faithful Imperial saint. The party didn't even slow as the wave hit; not until everyone was converted anyway. She-Who-Thirsts' laughter echoed with the last notes the discordant band played.
The Emperor fought valiantly to protect his precious Imperium; but weakened as he was he could do nothing to stop the wave. In his desperation to save his people he savagely attacked the world, ripping apart the minds of billions to get what he sought; and eventually he found it. Three secrets that might, just might, save mankind. Sacrificing all his power he wrenched thousands of worlds into the webway, crafting a single, massive crystal and a vat of dark liquid in this strange realm before destroying every access point into it. He smiled as he faded away; content with the knowledge that his people would survive, even though the universe might not.
And while similar scenes replayed for millennia in the Warp, the whole event took less than a picosecond as far as Madara was concerned; time and the Warp having an at best loose acquaintance. He had barely enough time to note the portal the demon made before said portal turned to a massive explosion before his frantically swirling eyes. The explosion swept over the planet In an matter of seconds, spreading thought the universe in a scant few more.
However, a few seconds was more than enough time for the Ghost of the Uchiha to act, he had been running laps around light since before he became host to the Juubi; when he cranked it up to eleven there was little he couldn't do.
Madara Motherfucking Uchiha just blew up the universe, bitch.
Who, if anyone, survived remains to be seen.
The End, For Now.