Not much here, yet. Except for the a note to self about the sequence which is required to activate the Chrono Cross -- Yellow, Red, Green, Blue, Black, White. The sequence must be initiated by the Time Devourer, usually via an OmegaYellow cast. Make certain Serge is at or near level 8 when this happens, and has stamina 7, and at least one other party member has some levels and is at stamina 7. Make certain to have some low-level elements of the appropriate colours! I was lucky in my case, the Time Devourer gave me the black I needed via Black Hole. I don't believe this is normal.