This game was a few weeks ago now, but as it was the Auld Enemy its still worth posting it up!
From the off the big threats where his Supercharged Whirlwind from FW (3D3 shots, S6, AP:-2 D2, and if stationary can shoot twice), the Stormeagle and its contents.
In my opening turn I killed 36 of his 40 cultists, and popped the Rhino whirlwind thingy and killed a unit of CSM Marines.
Playing Ascension & maelstrom that netted me 4 VP's in turn 1.
His Turn 1 was pretty quick with minimal damage to my army (3 Primaris Marines killed), and his cultists reappearing on my back line to do it, the Stormeagle managed to plink 4 wounds off the Repulsor and another dropped off the Sicaran.
End of Turn 1, 4-2 to me.
My Turn 2 was another firestorm of shooting, with me deliberately overcharing the Hellblasters (in the hopes of killing some for additional shots) to pop the Stormeagle, to be fair I should have done that from the start, and then thrown down a load of shooting at the contents, as it happened I did it the wrong way round and had wasted a chunk of shooting before using the Hellblasters properly!
I then managed to kill the unit of possessed that were in the Stormeagle, while beginning to whittle down the number of Cultists that reappeared behind me.
The Inceptors had a very successful deepstrike! , before charging them with my Intercessor squad that was reduced to 2 marines.
The charge was not my best choice, although Casualties meant these guys got hammered in the Morale phase.
This brought me another 5 VP's.
His Turn 2 had him get his charges off with his Daemon Prince, Warlord, Dark Apostle and the 2 units of Khorne Beserkers, engaging (and destroying) my Sicaran, and reducing the Repulsor to 1 wound from his Daemon Princes charge.
His Shooting was ineffective, with the Primaris staying locked in combat with the cultists and passing his armour saves.
End of Turn 2: 9-5
Turn 3, I knew I had to kill a load of his models to stand a chance, the Repulsor disengaged and backed up, the Heroes moved up to be able to charge the Daemon Prince if it survived my shooting.
The Marines began by opening up on the Beserkers, killing all bar 1 of them (enough to ensure that 1 character would remain immune.
The shooting at the Daemon prince chipped away 4 of his wounds, before in combat i charged in killing him with my Lieutenant.
At this point my opponent conceded with a Defiler, 1 unit in his backfield and two models left in the midst of my army he didnt have much left to challenge me, and by this point the score was 14-5 in my favour.
His last act was to kill my Intercessor with his three remaining cultists!