I know a marked prism can be attacked if she is in ocult state when marked but.... Can still cause damage to her while ocult?
I don't know what ocult is, but marked means they can attack without los, and you need los for a defender to damage an attacker. I don't see anything that says the attacker needs los to damage the defender though.
When a character is Hidden you can not trace LOS to him beyond 1-1 When a character is Marked you don't need LOS to attack (and make damage) to him. So, a Hidden and Marked character can be attacked and suffers Damage from
Yeah, Marked effectively hard counters Hidden (though, notably, it does still shut off things which specifically need LoS, like Hannibal's Coordinated Assault and Pointman).