Sprites ripped by Random Talking Bush.
The Mega blaster is a super combo Earthworm Jim used in ClayFighter 63 1/3 and ClayFighter: Sculptor's Cut, the super version of Laser Shot and can be performed with double quarter forward + button.
He shoots four blasts out of his gun instead of one, knocking off the opponent with the last shot. In Sculpture's Cut, he also yells "MEGA BLASTER!" when he performs the move.