Bound to the preacher's son Jason Blood on Earth-13, a twilight world where technology and magic exist together, Etrigan was rocketed to Earth from the planet Kamelot and defends his earth in the name of Merlin as Superdemon as well as leading the League of Shadows! A rhyming demon like his dimensional counterparts, Jason releases Etrigan and transforms into Superdemon via a rhyming verse.
"First spells the word. Then word's made law. A curse is strung. A sentence passed. Brought low by Grammar at the last. Thereby was demonkind confined. Enchanted in meter. Rapt in Rhyme. In verse and measure. Set in time. Where naming binds all things to shape, divides the Angel from the Ape--yet all that's measured must decay--all bars--all cages--fall away! Come fiery dawn! The Demon's Way! And thus, with time stretched far too thin for further wordy artifice, Instead these clumsy couplets must suffice--Quit! Quit now, The Form of Man! Rise Superdemon! Etrigan!"
- Superdemon transforming in Multiversity #2
Note: Superdemon technically cameoed unnamed in Superman Beyond 1 with the classic Etrigan design and from Earth 17 drawn by Doug Mahnke. The actual Superdemon appeared on a Multiversity: Society of Superheroes variant cover drawn by Frazer Irving but first appeared in the Multiversity Guidebook in comic as designed by Jae Lee and then starred in Multiversity #2 drawn by Ivan Reis. All were written by Grant Morrison