This involves two player characters: A wealthy cleric and a sorcerer with detect thoughts. They are cooperating whereby the cleric is giving gold to NPCs for free, simply asking them to pray to a god at a certain time of day once a week. The sorcerer is using detect thoughts on the NPCs to make sure he/she is living up to the bargain.
This appears in no way related to anything else that's going on in the campaign. To emphasize, these are random NPCs sought out in a crowd, not even regularly-occuring NPCs. As the DM, I'm humoring them, even keeping things fairly sophisticated in terms of mechanics: I've assigned simple character sheets for these NPCs and have been rolling a D20 + the NPCs religion modifier to see if they do it against a low DC. Most of the time, the result is: "Yea, they are praying to the god."
After which, I just move on, as it's not really advancing the plot. Of course there are ways that I could weave this into the player arcs: that kind of behavior is a bit manipulative or even vindictive, and could make for a character versus self plot device.
However, I think we're all kind of amused as it just being a comical silo theme that comes up every now and then. Of course it's impossible to read their minds and predict exactly what they are planning, if anything. It's also part of the fun to wonder what might be going on. Still, I want to map out as best I can what avenues this could open up down the road, just in the event I'm missing something obvious that might break the game. I would still reward their effort, if anything I'd just increase the difficulty slightly so that the main story arc doesn't become too easy for them if their buying of prayers actually skews the power dynamics in some way down the road.
Question
Is there any spell/cantrip or anything in the known 5e framework that scales really well with people praying at a certain time of day?
Best Answer
There's absolutely no reasonable way to break this
First of all, there are no game features that are affected by prayers. There are some game features that require the character themselves to pray (at least in a manner of speaking) such as the Cleric's Divine Intervention class feature, but none that care about the quantity of prayers.
It is sort of implied in 5e, and explicitly the case in some rarely used supplements from earlier editions, that prayer affects the power of gods.
Depending on the setting, any god you're likely to have heard about will already have anywhere from thousands to hundreds of thousands of faithful acolytes and layman worshippers. Bribing a couple of peasants is unlikely to have any significant effect here. Even if they somehow pulled off a grand scheme to raise the rank of some god over another, that doesn't really translate into anything the player characters themselves can make use of.
At best there could be a sort-of soft benefit, in the sense that if a god acquires more worshippers that would translate into somewhat greater prestige for priests of that god, which means they would have an easier time finding faithful who'd be treating them favourably, perhaps even in higher ranked positions. It's unclear to me if and how well bribery-induced prayer would facilitate such a development.
If you want to know what your players may be trying to accomplish I'm afraid there's no way around asking them. They may have an idea that they're working towards a very concrete goal, and rather than worrying about something like "game balance" (which again, nothing they did here would really affect directly) I would worry that there might be some fundamental miscommunication going on about how you and the players think the world works, which may lead to disappointment later down the road.