How does one get 4*, 5* champions

chuiku2

I always use the Premium Hero crystal to get Champions but I never get 4* or 5* Champions. How can I get more of the 4* and 5* Crystal Shards? Which events or story lines should I play? The higher the level I go, the more revives I use up and sometimes cannot even complete a few quests.

CapWW2

Play Act 1 a thousand times.

charaderdude2

Explore Act 3 for a 4*,Act 4 for a 5*