How to swear by a god?

Question

Suppose I'd like to invoke a deity for mild profanity: the equivalent of "yes, by Zeus!" or "no, by Zeus!".

I know that in Attic, μά + accusative was fairly neutral; a simple μὰ τὸν Δία, possibly augmented by other particles for nuance, would serve my purposes. But what if I want a stronger or more emphatic (or florid) oath? Or what if I would like to swear in a dialect other than Attic? What other options do I have?

(E.g. νή, ναὶ μά, other more interesting alternatives)

I'm primarily asking about Greek, though Latin would be good to know as well. (To my understanding in Latin you just use the vocative of their name?)

Answer 1

This answer only concerns Latin; I will leave Greek to others. Vocative is not the way to go here. It is used for addressing the god, not for such exclamations. (At least I have never seen it in such use.)

I would swear using pro (or proh) and a nominative. Pro dolor! Pro Iuppiter! See, for example, these search results for the second phrase.

Another option is per with accusative, but I am hesitant to use it alone and it does have a different tone. Plautus — in at least Menaechmi, Miles Gloriosus, and Amphitruo — uses the expression per Iovem (ad)iuro, "I swear by Iuppiter". You can drop the verb to get "by Iuppiter!", per Iovem!. I found no attestations of this without a verb, but it would make sense to me as an elliptic exclamation.

If you want to swear by Hercules, there is a separate word: meherc(u)le. Repeat the linked search for these words to find examples. There are also separate words for Castor and Pollux as TKR reminded: ecastor and edepol. Another similar fixed phrase, suggested by C. M. Weimer, is (pro) di immortales.