Ovid speaks of the daring love requires.

Per Styga detur, Stygias transabimus undas; sunt mihi naturae iura novanda meae.

If passage be granted through the Styx, we will cross over Stygian waves; the laws of my nature must be changed

Per: through

Styga: Styx (accusative singular)

Detur: if it be granted

Stygias: Stygian (plural adjective)

Undas: waves

Transabimus: we will cross over

Sunt mihi: I have

Naturae meae: of my nature

Iura: laws

Novanda: must be changed