Not much to say about this card, except I like how it is very close to the Heavy Rain treachery in Scarlet Keys, so we have consistent rain mechanics.

The reason I am writing this is a maybe helpful suggestion: I was going into the mines on day 2, and I didn't like the flavor of rain underground. In case this comes up for you and you feel the same, and you own The Forgotten Age (as you should), in the encounter set Forgotten Ruin, there are 3 copies of Deep Dark. I am switching these out for this scenario on Day 2. They are not identical, but they both target your clues in a way. Deep Dark seems weaker, but it's a good flavor fit I think. In 4 player, Deep Dark could be worse if it comes up at the wrong time.