I know some people like a bit of historical background for battle reports so here is mine...
Abbadon holds a grudge against the Adeptus Mechanicus dating all the way back to the heresy due to what he considered betrayal when a certain Admech battle group deserted a tea, of Sons of Horus he was leading towards the end of the heresy. Several millennium later Abbadon is finally able to exact his revenge after having discovered a means to travel all the way back in time to that point. He convinces Kharn to join him and bring along a Khornate war party to settle the dark grudge. Kharn in turn calls upon a mighty fallen champion of Khorne, Kharandus the Skull Splitter. An ancient evil Contemptor dreadnaught, Blood Red, is also re-awakened to serve as well.
The battle takes place on a terraformed moon of Mars named after a son of Ares, an ancient God of War - Deimos. A secret forge is located on the satellite which Abbadon wants to destroy after absconding the dark technology kept there. Just prior to their arrival the Adeptus Mechanicus detects a warp anomaly and quickly muster an ample army so as not to be caught off guard.
The forces of Chaos arrive via the warp several kilometers from the forge and immediately begin the march to war...
1st Turn - Admech
This turns out to be a rather quick turn. Due to my deployment most of my armored units are out of range. The majority of the Admech force move and then run (if possible) to close the distance. Most of their shooting is focused on my Flesh Hounds they have line of sight to this turn. Most of the hounds are tucked out of sight and with the 4++ invulnerable save due to their proximity with the Chaos Typhon I only lose two to three. Note the Urasarax moved to within charge range of the Flesh Hounds but I won't be able to assault them this turn due to their scout move. The Typhon also loses a hull point to shooting as well. Both Thanatars get good rolls for their run move and are close as well.
1st Turn - Khorne
The Chaos Contemptor arrives via drop pod and I place him close to one of the Thanatars to my left between two ruins with minimal scatter. I know there is the risk I'll give up First Blood but I felt I needed an expendable heavy hitter to hold off the gigantic construct in order to keep it from being able to assault my Flesh Hounds next turn.
The Flesh Hounds move up and further to my left now almost completely hidden from the Admech guns.
Shooting is focused on the Urasarax - mainly from the Greater Brass Scorpion and Typhon which gets a large scatter for its blast. The Contemptor also hits them with its plasma blaster as well. I'm able to whittle them down to just three and one of the remaining Urasarax only has a single wound left.
Thus ends the first turn with neither side scoring First Blood.