If you're looking for ancient curses, defixiones ("curse tablets") are a good source. For example, here's one from Britain:
The reconstructed text reads:
Domine Neptune, tibi dono hominem qui (solidum) involavit Muconi et argentiolos sex. Ideo dono nomina qui decepit, si mascel si femina, si puuer si puuella. Ideo dono tibi, Niske, et Neptuno vitam, valitudinem, sanguem eius qui conscius fueris eius deceptionis. Animus qui hoc involavit et qui conscius fuerit ut eum decipias. Furem qui hoc involavit sanguem eiius consumas et decipias, domine Neptune.
Lord Neptune, to you I give the name of the one who stole one gold and six silver coins belonging to Muconius. Thus I give the names of the one who took them away, whether man or woman, whether boy or girl. Thus I give to you, Niskus, and to Neptune, the life, health, blood of the one who was in on this scheme. The mind that stole this and that was in on it, may you take it away. The thief who stole this, may you consume and take away their blood, lord Neptune.
Translation and emphasis mine. This curse addresses the deities in the vocative case, then prays for something to happen in the subjunctive. Personally, I'd call this an optative subjunctive, since the writer is hoping that bad things will happen to the thief.
Off the top of my head, I can't think of many Classical prayers in the imperative outside of literature, since most people can't really order the gods to listen to them. (Literary examples include the necromancer Erichtho, who orders the gods to do whatever she wants in a supreme act of hubris. It seems to work out reasonably well for her.) But they might exist; I'll leave that for others to answer if so.