[IAmBatman]

Cool stuff. A few notes:

1) I think Criminal is at least worth considering as a class. I really like the idea of he and business suit Lex having that synergy.

2) Is it 3 attack dice or 4? For not being able to use it more than once and for sacrificing defense afterwards for the rest of the game, I almost think it should be 5 ...

KRYPTONITE HEART SPECIAL ATTACK
Range 1. Attack 4.
Any figure adjacent to Metallo is affected by this special attack. Roll 3 attack dice once for all affected figures. Each figure rolls defense dice separately. Kryptonian figures cannot roll any defense dice against this special attack. After attacking with this special attack, Metallo rolls 2 fewer defense dice for the remainder of the game. Metallo can only use this special attack once per game.

3) It's not 100% clear here - does he get to roll only if you start to leave an engagement with him or if you start to move in general? The triggers here seem to imply both and don't make it completely clear which is true. I'd assume from the text that it's the former (when leaving engagements only) but I think we've got to be able to make that clearer in the first part of the first sentence.

CLAMP AND CLAW
When an opponent's small or medium figure that is engaged with Metallo starts to move, instead of rolling a leaving engagement attack for Metallo, you may roll the 20-sided die. If you roll 14 or higher, the figure receives 1 wound and cannot move.

Cool stuff overall! I like the take on Cyberclaw that is a bit more interesting and not as gamebreaking!