Hey everyone! I was just curious if there were any rules regarding a specific, admittedly niche type of interaction I have noticed popping up when I look at some monster stat blocks. There are creatures that are immune to some types of damage, but not necessarily the conditions that attacks that deal that type of damage would incur. For instance, in the case of a Iron Golem against a Mindflayer, say the Mind Flayer uses its Mind Blast on it and the Iron Golem fails its saving throw. Now, the Golem, being immune to Psychic Damage, would suffer no damage from the hit of the blast, but as it is not immune to the Stunned condition could theoretically fall victim to the secondary effect. Would the Golem still suffer the secondary effect if it was unaffected by the primary effect, or would the immunity to the damage negate the secondary effect entirely?

It depends on how the feature is written The mind blast feature is written in a way that doesn't preclude the second stunned effect if the creature takes no damage.

A feature that would preclude the additional effects would be written similar to “a creature that takes this damage is stunned.”