The most I remember is that 2 guys (maybe teens) are out to save their girlfriends.
There’s a scene that takes place in a desert and they come across a shack with a dark skin man inside. He gives them advice or weapons (can’t remember) before they continue their journey.
They arrive at a castle. When they sneak in, there is a party. (Black and red background / lewd content)
The guys split up and they each find their girls. But instead they are shapeshifters, or girls that can shift their looks to appear as them.
In a scene, one of the girls try to sleep with the guy, but as he refuses, she shifts her face to look like 2 or more other women.
The guy gets away and warns his friend that the girl whom he is with is not his girlfriend.
Eventually they find their girls and escape the castle, only to be followed by a monster/dragon (or maybe a man that transformed into one).
In the end, the guys save their girls.