Damage cap on what? Skills? I don't think most skill damage caps can be reached yet with our equips, unless you have Kirin/Belial and use another one from Friendlist. And having Kirin/Belial is hardly a matter of skill.
I think the only damage cap I've reached is Pumpkin Artemis' nuke, but I need to be using Kirin against Water element to hit that. Don't even come close otherwise.