What zeta first for CLS?

CUP anti CLS Meta.

It binds all things. Because of the turn meter gains. They're very helpful, and maybe the most useful overall to luke.

Moving to appropriate sub-forum: Squad and Character Strategy

IBAT. The leader zeta is ok, the other one not very good IMO, as you will generally want luke in offensive to deliver major damage. IBAT is good for Luke and his group

I started with Learn Control, which gives him +50% critical avoidance and +100% tenacity in the opening moves of the battle until he gets a chance to activate his Call to Action. I added Binds All Things second, for the TM gain. I haven't added his leader zeta yet.