John was an extra-mutated Gadunka summoned by Blackout to fight Rakoua. He had protosteel armour which could absorb any attack, increase its power fivefold, and shoot it back at the attacker. He could also fire lightning out of his mouth, though, according to Blackout, he was unlikely to use this ability.
He tried to eat Rakoua, who slashed his stomach open, sent him to the Zone of Darkness to be eaten by a Zivon, only to change his mind, teleport John back, stuff Blackout into his stomach, and teleport him back to the ZoD. Somehow, John managed to reflect this attack back at Rakoua, and then tried to eat him again.
He then tried to eat ~Bitil~ "over and over again", only to be shot with a Cordak. He then ran away crying.
John reappeared on Mordor during the Uterio War, and killed some Daleks. John Stormer then ran up to him, and the Gadunka ate him, spat him out due to indigestion, and blasted lightning at his remains.