Giant, tent-pole superhero movies, with huge, multi-film characters are a strange undertaking. Secrecy is paramount, so actors are often unaware of exactly what part they are auditioning for. This is achieved by having the actor use scenes and lines from something else, that has similarities to the character actually under examination - thus allowing the director the opportunity to see how the actor would be with the desired tone, while keeping everything under wraps. This is how Jason Momoa auditioned for the role of Aquaman.