Do DC and Marvel have big official reference books on all their characters powers and abilities and the state of their universes for the writers to read? Is it mandatory? feel like some writers don't pay attention to the characters they take on in terms o

I don’t know about big reference books. The only big reference ‘bible’ thing I ever got was when I was working on Superman in Action Comics, and it was mostly a huge stack of copies of various key stories with some notes in there. It was helpful.

There was never a hard and fast limit on powers, and inventing new things is always encouraged with new characters. With the icons, you’d have to get it approved. I did once have to get approval for Wonder Woman to survive a nuke, which I thought was perfectly fair.