Exploration

Overview
Normal 6 stars exploration requires two 8 star heroes  and  one filler except the exploration for the summoning ticket which only requires two 5 star heroes.

5 stars exploration requires one 8 star hero and two filler.

4 stars exploration requires two 6 star heroes.

3 stars and 2 stars exploration require two 4 star heroes respectively.

1 stars exploration requires two 3 star heroes.