he poem that releases Etrigan is: Yarva Demonicus Etrigan.
Change, change the form of man.
Free the prince forever damned.
Free the might from fleshy mire.
Boil the blood in heart of fire.
Gone, gone the form of man,
Rise the demon Etrigan!
Jason Blood’s first transformation into the Demon occurs when reading the inscription on the surface of a stone tomb:
Change! Change, O form of man!
Release the might from fleshy mire!
Boil the blood in heart of fire!
Gone! Gone! — the form of man —
Rise, the Demon Etrigan!!