No umbral malady immunity but healing in gloom.

[Melee Sniper]

I'm fighting a free city and cast pall of gloom on their city, but all their units can still heal. I checked them out and I don't see anything that gives umbral malady immunity.

[Blanch Warren]

It either doesn't work on free cities, or it doesn't work inside cities. It should, but they'd probably have to rethink their game design.

If someone is out there spreading gloom, free cities should probably be aligning with eachother or the enemy. I.e. more dynamic diplomacy considerations.

[Pantagruel]

I've never seen gloom work on any type of marauder, just empire units.

[MattStriker]

Free city units are immune to umbral gloom. They get a LOT of bonuses. People like to complain that the empire AI materializes armies out of thin air (it doesn't, it recruits normally just like the player) but free cities absolutely do that and you can watch it happen after they've taken significant losses somewhere. Free Cities also don't have an economy to worry about which means you can do hilarious things like sending a dozen T5 units to a vassal via Rally without them ever getting upkeep problems...