To rank or not to rank champions?

Champion rank ups,

depend on the fact that you're in this for the long haul. If you have 1 cosmic champion and they are "not worthy" overall, but are a strong addition to your team then, by all means rank and level that champion. Using your brain in the contest is an absolute, but realising that taking a mediocre champ to rank 4 only to open a crystal and get a demon champion of the same class, is a serious pain in the butt.

T4 Catalysts 

are tough to come by unless you're in a hardcore alliance, so make sure you're being smart about using them on champions that are worth it.