What exactly is the vast glub, vast honk, and vast croak?

The Vast Glub was a psychic shock wave released by Feferi’s lusus that killed every troll in the troll’s universe except the Condesce and Feferi. The twelve trolls we know were able to escape it because they had already entered the Medium. The Vast Honk is the sound Lord English released once he had emerged from Doc Scratch’s body. The Vast Croak is the sound that the Genesis Frog will release when he finishes growing in the middle of Skaia.