So, I think we found a huge, sticky loophole and I can't find anything in the rules to tell me I'm wrong. So I thought I'd let ya'll tell me.

We went into Undimensioned and Unseen (DL) and scrapped our way through to the last Brood, when our Roland drew his Universal Solvent (courtesy of the Blob That Ate Everything).

Now, the wording on Broods reads: "...and cannot be damaged or attacked except using the ability on Esoteric Formula."

The wording on Universal Solvent reads: "Spend 1 supply: Choose a non-Elite enemy at your location and test INT(X), where X is 1 more than that enemy's remaining health. If you succeed, that enemy is defeated ."

Universal Solvent is neither dealing damage or an attack, enemy just has to be non-Elite.

Is this legal? We drew Universal Solvent on our last Brood, but had we drawn it our opening hand...

Yeah, the broods are a pretty funny example of enemies that maybe should be elite, but aren't.

I'm pretty sure it works the way you expect: the enemy is defeated. There have been a few wacky methods of defeating the broods even since before they were released, specifically Mind Wipe and Waylay, but the Universal Solvent seems ridiculously efficient.

I still like mind wiping them 😂

Yep, this is totally legit. There's a survivor card that does the same thing, an instant defeat on a non-Elite enemy - "Waylay"

Universal Solvent, Mi-Go Weapon, Pet Oozeling and Monstrous Transformation are all inherently capable of unbalancing the game when they interact with certain scenarios (or indeed by themselves). Lt. Wilson Stewart is also really powerful, especially for certain investigators, but not in the same league.

So yes, it's a "broken" interaction, but I wouldn't expect it to be "fixed" in errata - the designers have had years to address Calvin + Monstrous Transformation and haven't, so it seems like the side scenario rewards are allowed to have unintended interactions. Use with caution!

I feel like they went particularly wild with the Blob rewards since the scenario is thematically "non-canon," so they don't expect anyone to slot it into a serious campaign. In particular, the Mi-Go Weapon can forcibly move Elites, violating one of their established immunities and rendering some scenarios broken or nonsensical (eg Blood on the Altar).