Newt wasn't pleased about being humiliated by Graves, so he stuns him and locks him away in his suitcase.

Graves soon finds out what Newt has in mind for revenge. While he's jinxed with some immobilizing spell (that still lets him talk), Newt has one or even several of his beasts fuck Graves savagely while he watches and touches himself.

Bonus for Graves begging for mercy/trying to explain that what Grindelwald did wasn't his fault, but Newt doesn't care, he's too turned on by watching Graves' helpless face twisting in pain as large carnivores fuck him senseless.