T4CC proving grounds/ grandmaster daily quest
As the game and players have progressed it has become clear that to play some of the competitive team modes at the medium to higher level you need champs at the level of 4* 4/40 or higher, I know this has sort of been addressed in the past and some rewards may have been buffed. That been said the current rewards in the proving grounds are pretty bad, it may not be the main place to collect catalysts but it should be really and I feel the rewards are the reasons.
As a fix I propose that you could increase the rewards in the expert proving ground slightly so that 100% exploration over 7 day collects enough fragments to form a full catalysts.
You could also and a master difficulty onto the grandmaster event that would reward a small amount of fragments for every class T4 catalyst.