he claimed to be invulnerable in Green Lantern
just after Kyle got the ring MF killed Kyle's girlfriend.... Kyle got pissed off (understandably) and smacked MF around.... the his ring ran out of power... eventually he recharged it .... during the fight he managed to put a hole through MF's kidney region.... then stuck him in an electric chair.... he was gonna kill him until the police showed up
to answer the question of how strong MF is...... i don't know
shutup