Diabolical Soothsayer Re-roll

If you use Alliance of Agony to give a Haemonculus the Soothsayer trait, who gets the re-roll? The trait is worded to give the re-roll to your warlord. I'm assuming RAI is the Haemonculus with the Soothsayer trait as usually he would be your warlord to have the trait in the first place. But RAW would be the Archon, as with Alliance of Agony he's your actual warlord. I'm not looking to be cheesy here, I'm just unsure how this one goes.

Haemonculous. He is the warlord for that trait for all intents and purposes. He just does not give up a "slay the warlord" point.

Yea that's how I'd assumed it would work, thanks!