Some obvious spoilers incoming.
So, apparently "Giant Martian Mech Warrior Battle" is/was a thing in Mars. Top reason to save Earth? Biscuits and raisins.
Couple of theories:
a) Anyone else thinks that this series is going for some sorta paradox where ritual that was supposed to save Mars is actually responsible for its destruction in the past?
b) Mars child, can he be young J'onn?
All in all it continues to be an entertaining read.