Training Ground/Practice Mode
I have an idea which is solely for new comer to the game. A 'Practice Session or Training Mode' where we can test our newly acquired champs' skill sets or moves without any rewards or costing anything.
In training mode, there should have 'Revive' to keep the training infinitely. It should come up with different difficulty levels from 'No Action' to 'Expert', where we can safely explore the champs and improve our skill before entering the battlefields.
Duel/Vs isn't what I expect for training infinitely as they have their own strict limitations.