In Italy, this movie is known as Ercole e la Regina di Lidia (Hercules and the Queen of Lydia) and it’s loosely based upon various Greek myths and the plays of Aeschylus and Sophocles, as envisioned by co-writers Ennio De Concini and Pietro Francisci, who also directed. It’s also the second — and last — Hercules movie with Steve Reeves in the lead.
Hercules has been brought in to settle the battle over who should rule Thebes between brothers Eteocles and Polynices. However, a magic spring looks so refreshing and Hercules is hypnotized by a harem girl and becomes the kept man of Queen Omphale of Lydia (Sylvia Lopez, who sadly died the same year this movie was made), who plans on sleeping with our hero until she gets bored and turns him into a statue.
Luckily, Ulysses is on hand to help him get his memory back, just in time to decimate three wild tigers in order to rescue his wife beloved Iole (Sylvia Koscina). Then, our hero realizes that he should just let the two brothers kill one another.
Wrestling fans will be happy to see Primo Carnera (he was also a boxer and known as the Ambling Alp) show up as Antaeus.
Mario Bava served as special effects supervisor on this film (he was the cinematographer for Hercules and Hercules Conquers Atlantis; he would then direct the incredible Hercules In the Haunted World), which you can definitely see in the foggy dream sequences.
While Reeves would leave the series to Reg Park, the two Hercules files he was in would be successful all over the world.
You can watch this on Tubi with Mystery Science Theater 3000 riffing or check out the original on YouTube.