Like most people here I am gravitating towards a single Duplicity batallion and a Magic supreme command. I tried making room for more, but find that I can't do that and still keep all the units I want to bring to the table. For the supreme command I am considering going for Ahriman, a terminator sorcerer, and a daemon prince.
If the enemy is bad at spacing things out and clumps up, then I'll take the cult of magic warlord trait and relic on the terminator sorcerer, and teleport or deep strike him up. Use chaos familliar to give him the infernal gate psychic power, +1 to cast from familliar, +1 to cast from relic, +1 damage to all mortal wounds from the warlord trait. With possibility for another +2 through the stratagem if I've managed to get my rubrics and scarab occult in position through the risen rubricae and black matter crystal, or the deep strike strats.
If the enemy is better at spacing, coming towards me anyway, or I want to save my CP for other things, then I'll just give the relic and warlord trait to the daemon prince, and load him up with infernal gate and the reroll power. Cast rerolls until people get close, then go nuts with AoE powers.
Fun fact - with duplicity you can actually redeploy a single unit 4 times before your first turn has ended. Rubricae rise from the sands, as a plan centuries in the making comes to fruition - but no, it was just a cunning ruse by a Duplicity magister, they are actually over here. But no, they crushed a dark matter crystal and now they are over here instead - but alas, that was just a mirage conjured by the cult of Duplicity sorcerer - they were actually over here the whole time, drinking beer and snickering. Supremely silly stuff, but I love it. Very "just as planned".