A powerful ancient artifact reacts to the wearer's escalating arousal, triggering an irreversible species transformation at the moment of orgasm. The transformation process creates intense physical sensations that intertwine with sexual pleasure, blurring the line between pain and ecstasy. The artifact may demand regular use to maintain the new form, creating recurring scenes of forced transformation during intimate moments. Secondary effects could include amplified libido or attraction to the new species' natural mates.