Holy crap, it's my turn for the Skeptic's Circle! Been waiting for this for a while.
Up next will be the Great And Powerful Box and person who runs the Skeptic's Circle, Orac. Here's some posts with an overly nerdy theme tying them together, have fun.
Okay, men (what's this about women? No far-future 41st millennium space babes for you!) we've come up with a plan to force the forces of Chaos off Askzilgtiv MDLXIIIV and destroy their last stronghold and surrounding camps.
First, Colonel Devan of the Holford Watch 571st will take out their evil heretical communication devices. This will allow other attacks to go off without them being able to coordinate their defense, so they we can slaughter them easy.
After that, we will leave behind Colonel Bronze Dog and his Bronze 450th to coordinate the defense. With his special defensive tactics and his expertise in spotting the enemy, he will be perfect for defending our camps while we strike at the enemy. Also, he has great skill at digging trenches.
Colonel PalMD of the Denialism 535891423798571293579175213957213962139865th will take out our Chaos-tainted former brethren. They are the least well-defended, since they are mostly injured, and we should take them out while we can. Their famed heavy bolter teams should make short work of the nearly unarmored enemy army.
Colonel Christina, your troops are famous demolition experts, so you'll use underground tunnels to get under and destroy the foundations of their Chaos chapels using the Mythbusters method. This should be another devastating blow to their morale; the Khorne cultists might even end up committing suicide to please the Blood God. Why they wouldn't just try to murder us and die in the attempt, since all bloodshed pleases the Blood God, I have no idea.
The 62.534th Pancakes led by Colonel Bing will take out their ugly-ass Nurgle daemon summoning grounds and their Great Unclean Ones, and then move on to the trippin' Tzeentch grounds and destroy the Lords of Change. We can't let their daemons get to the main battlefield and drive us batshit insane, and the Grey Knights owe you a favor, so you get the job.
Matt and his 571 Pooflingers will use their sniping ability to assassinate the new Chaos leading sorcerer, Ahrasoih, who took over after we captured the previous one, who was his father, and sent him off to the Ordo Malleus, by coordinating their shots to all hit him at once and overload his psychic shield. Then shoot him again, just to be sure. Oh, and then they'll rip apart his corpse and burn it. Should take out their command structure. (The Chaos aren't the only crazy ones in this scenario... the Imperium is pretty goddamn crazy too. Though, technically, the Emperor was an atheist and actually made it illegal to worship him as a god, which is interesting since the entire Imperium considers him the God-Emperor of Mankind now. So the Imperium being insane religious nuts is partly Horus' fault for putting the Emperor on life support. Aaaaaaaaaaanyway, back to the circle!)
Colonel Akusai, you and your 35th Action Skeptics's flamethrowers will fight fire with fire by destroying a nest of Horrors and Flamers which will be teleported onto the battlefield if not destroyed. A Vindicare assassin is already in position to take out their sorcerers when you arrive, so that they can't teleport out the Horrors. Why not just have the Vindicare Assassin take out the sorcerers and not send you there? So that they don't have a chance to send replacements, of course! This should take care of their daemonic reinforcements.
Using new techniques taught by master tacticians, Skepdude and his 3.14 Skepfeeds will do... uhhh... something? What is it you can do with that, anyway? I'm guessing you learned to fight on the front lines or something, so I'm sticking you there. There, that should work. Go kill some Khornate berserkers and a Noise Marine or 5. If you're lucky, you might even encounter a Plague Marine or a member of the Thousand Sons!
Colonel Stacy of the 6th Sunclipses will use what appears to involve math that I can't comprehend to aim his artillery units and blow shit up.
Colonel Theo of the 1225th Humbugs will use his twin abilities of talking lots and annihilating Chaos podiatrists to talk their footcare professionals to death.
Colonel Podblack is going to slaughter their women and children for shits and giggles. Also because they're corrupted by Chaos and are slightly more of zealots then the men, but mostly shits and giggles.
Lastly, while those coordinated strikes destroy their shit, we shall have Colonel-Commissar Perky vox us some inspiring hymns (not a commissar's job, you say? So what? says I.) so that it seems like the fight against Chaos actually has some meaning instead of being endless and unwinnable. (Interpret this as it relates to skepticism how you will. I'll tell you if you're correct or not. =P)
The end result will look something like this:

Good luck, and try not to let the Warp get to you and drive you batshit insane! I'd hate to have to execute you.
Oh, and on the note of executing, if you object to your rank of Colonel, I'll use my rank as General-Commissar to shoot you for the Greater G- err, I mean, for the Imperium. Because of... uhh... cowardice. Yeah, that'll work.
Open the cage...
Close it back up...