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.