Unless/until they change Codex Arena, there's no point making builds for it, as the skill options change randomly every day. Well, they say it's random but I think that's an escaped from the rings of Sol 7.
Codex Arena could have been something awesome, but they totally screwed it up. It should have been a place where players are forced to use a rotating variety of premade builds that teach them a wide range of strategies, tactics and mechanics. What we got was a monument to the chronic incompetence of the decision makers.
I'm leaving this section open as a temporary storage for Codex Arena builds.