Sound Ideas, Sound Design - Processed Elephant Screams - Surreal, Good For Horror Movie Demon Scream, Sounds Like Animal Is Scared & Upset, Heavily Processed & Pitch Shifted, Minor Distortion On Peaks

This sound effect can be found on Soundstorm Sound Effects Library, which was made by SoundDogs. They're modified versions of Sound Ideas, ELEPHANT - VARIOUS SNORTS, GROWLS, TRUMPETS, ANIMAL.