Set's introduction in Throne of Fire. Apparently, he likes the name "Rockin' Red Reaper" better than "Evil Day". Then again who wouldn't?
The Serpent's Shadow
Shelby is both adorable and hilarious beating the enemy magicians on the butt with her wand and chanting 'Die, die'.
The interactions between Drew and Sadie are this and awesome.
"Sadie, please do not call the Destroyer of Souls 'poochiekins'."
The return of Hindenburg the camel. "If you're confused think how the criosphynx felt."
The chapter where Amos/Set is fighting with Sarah Jacobi. Sadie rushes in to help her uncle, only to be nearly killed by Jacobi, and then Walt/Anubis steps in and takes care of her. The words exchanged between Set and Anubis is just lulzy: