Quick question on how the Chaos Warlord's interrupt works with AoE. Normally when you assign someone damage, you would then interrupt and increase that damage by +1. When you AoE, you don't choose a target and instead assign damage to an entire group all at once. The way we had been playing it is, since all damage is being assigned at once you interrupt once only increasing the damage on one person instead of on the entire group. After watching a game on Youtube, I noticed the streamers were increasing the damage on everyone caught in the AoE, so I decided to ask here if someone could clarify.

Card reads:

Interrupt: When damage is assigned to an enemy unit at this planet, increase that damage by 1.

So I think you may have been playing it wrong. If you have say, Bloodletter in play (who has an AoE of 3) and you exhaust him to trigger his AoE, then every enemy unit is assigned 4 damage.

It's a nasty little ability!

Also note, that while Zarathur boosts the damage of AOE by 1, you still get a chance to shield each unit that took damage.

Every time the trigger condition is met the interrupt has a chance to resolve. You assign damage to multiple units, so that means multiple opportunities to trigger.