Love it, when MC meets Kara you should make MC tell a tale of a life as "Invincible" something that can make her relate to him, with MC being a overpowered alien she and Supes could enjoy the story
easiest(and laziest) way to kill joker would be with the flu. it worked for war of the worlds. and think about it, the joker dieing because he got a cold
Thanks to the author for the new chapter and the author let there be a world of Ben 10 and Warhammer (40k and fantasy, the age of Sigmar) for the main character