While playing The Delve last night, I ran into a situation where there was a unique master Broodwalker on the map as well as goblin archers. I'd killed the master goblin archer so only the minion archers were left. Their activation actions basically had them try to engage the master goblin archer first, which was dead. They would then try to engage any other master monster.
My question is: since the Broodwalker was the only master, would they actually engage it? Master Broodwalkers have hazard squares surrounding them, which would cause them to die at the end of their activation. In this case engaging with the broodwalker would be the only thing the archers could do.The RtL rules say if an available monster action would result in the monster being defeated "before it could otherwise affect a hero", which is a tad vague. I assume the archers would just avoid the broodwalker in this case?