Hello can someone please tell me what counts over the other rule?

For example i have the Chaoslord, he is stunned by a unit Golems and then attacked by an Archer-Unit that causes 1 Retreat during the attack step.

Will the Chaoslord suffer damage because of the Retreat- Result while he is stunned, even when he has his Immovable - Ability?

Greetings Tom

Immovable reads:

" When a unit with the Immovable ability would be forced to retreat, the player may ignore a number of those retreats up to the number following the unit’s Immovable ability"

Stunned reads:

"A player cannot move, attack, counter, or retreat using a stunned unit. If a stunned unit is forced to retreat, it suffers damage instead (unless it is supported) "

So, would originally the single flag force the unit to retreat? Nope, because of Immovable. Hence, Stun does not trigger on the first flag.