Were I GMing, if such a thing as demonic reprisal would be in the cards, during the night I'd have a dream - y'know, Desna's whole... thing... that warned of the possibility of retaliation and maybe gave a vague interpretive hint as to what to expect.
Vague enough that it's not helpful to accurately predict when (because dream-logic), but crunchy enough that they have some idea that it's coming and maybe even can put the pieces together about what (or who) they face.
Also,
Freehold DM wrote:
as demons do not let go of their worshippers lightly.
... is very true, but they're also busy and chaotic - while certainly and entirely capable of long-term planning, "taking revenge 'cause a tribe of trogs" is rather easily lost in the face of things like, "prevent rival from axing me in the back" or "that battle that literally spans continents I was gonna do today."
As a result, I'd have a select, specific limit to how much any given demon is willing to "spend" on such a petty thing. Obviously the first wave would be the peons, the second would be slightly stronger, the third might get serious, and the fourth, if any, would be tough... but it would fit neatly into leveling up.
(As an aside, the PCs would also be killing more demons, which, you know, win/win.)
NH Only; or, I guess, fellow GMs:
As an aside, I do so love both the Faction system and the Mythic system. It juuuuuuuuuust so happens that this sort of thing neatly fits into both.
Now, this wouldn't count as a full on mythic rank accomplishment, and I know you like the hero point system better, but I could see this equate to a lesser mythic trial - maybe like a stepping stone on the way to "mythic" (whatever that means in your games).
As to the factions, the ever-vague religious faction is super useful for this sort of thing - it's important to remember, though, that it should be more of a rough guide, not-so-much "hard" rules - maybe something you even keep notes on in the background instead of them keeping track of their Prestige Awards (Total or Current).
This is from Shattered Star and has somewhat significant spoilers in that it provides one solution to one part of Book 2, but it's not like it's not fairly obvious once you're there.
I'm just looking for player feedback: "That would make me feel really empowered and cool," vs., "The GM's a power-tripping jerk again. I wish he'd stop."
** spoiler omitted **...
Personally I think it's good.
I think it really helps reinforce your "all actions have consequences" world-building ethos.
Spoiler:
As for the NPC, it's right in line with the now high-level paladin of Sarenrae working in Underbridge (she came about from their earlier RotRL campaign). Adds NPCs to the world that the party has connections to, and that's always something that can come in handy even down the line.
As for the deific assistance...since it's divination spells it's guidance rather than direct intervention, and players can always screw up and ask the wrong question(s) or word them poorly. That's even before you get to the issues of interpretation of the answers.
Granted, I've read most of your campaign journals, and I know this group doesn't really *need* additional encouragement, but it's consistent with how you handled your Runelords campaign and it gives them another moment to remember.
I can't remember who the band was that did the song about a girl who got off by dressing like an animal. I know it was called "Furry Lisa", but the band escapes me. Maybe Smoking Microwave?
What was your favorite Broken Toaster song? Mine was the one about defrosting a freezer. I think it was called "Water Under the Fridge".
I liked 'Smells Like Clean Ovens', personally.
'Laura and her Faulty Hand Blenders' were another good outfit. Acoustic-y female-led indie-folk, kind of similar to Joan Osbourne or Alanis Morissette, but with a country twist!