Dirt Simple Domains (OSE?)

 

dunno the source, alas

Thinking (as usual?) about clerics. You know that I like gods with some personality. But there's certainly an aesthetic space for something a bit more one-note. Sometimes all that is relevant to a game is that such-and-such shrine is dedicated to the god of fire, or my cleric worships the sword-god, or this blade is holy to the god of frogs. The assumed cleric of an old school game (I'm using OSE as the example, cause its easy) is devoted to the god (possibly God) of light or law or life or something, or conversely to evil/chaos/death. They don't often have strictures, at least not by default, that would prevent them from, say, graverobbing. They're just supposed to, vaguely, advance the cause of good.

So, let's think similarly about the cleric of the god of frogs. They aren't bound that "thou shalt always be slimy" by the trickster frog Glorn. They worship simply the god of frogs, and will try to "advance the cause of frogs", whatever that entails, but in the same vague way that the fighter wants to avenge their parents. When you have a cleric like this, here is what you can do:

First, determine if the deity is lawful, neutral, or chaotic. You can pretty much just let the player pick, or use whatever alignment they are gonna be. This tells you if they are going to use the normal or reversed version of spells, of course.

Then, pick whichever spell on the cleric spell list is least fitting to the god, and replace that with the most fitting spell from the MU spell list of the same level (or illusionist/druid spell list, if you are using the full rules). This can be a bit tricky with only the MU spell list since they can be a little generic, but remember that being old-school doesn't mean we are banned from reflavoring things. For instance, for the god of frogs, I would replace Light with Shield (I would choose Sleep, but we all know Sleep is a bit overpowered)

When the cleric reaches higher levels of spells, repeat this process with the new level, taking into account any fun flavor your cleric mentioned about their god. Our frog god at second level will lose Bless and get Hypnotic Pattern. 

Finally, if you'd like, you can replace Turn Undead with a category of creature that the god would be opposed to. You could also Turn that category as well as undead, maybe increasing the effective HD of the turned creature. I think the god of frogs would be neutral on the subject of undead, but would rather loathe birds.

I don't pretend that this is a new idea or houserules, I just wanted to write about it. I might write up a short list of simple gods like this just for fun later on. I think if I were to add clerics to Fifth Fantasy, it would be in a similar vein.