Hero Tavern

Fusion:

Merge and upgrade the hero star, and the higher star will be upgraded to a higher hero level.

Sacrifice:

Sacrifice heroes can obtain certain advanced stones, godheads, and other materials needed for hero training.

Once your bag is full of hero cards, sacrifice some to exchange for resources to boost your hero team.

Reverse:

You can use $BDD to return heroes above 5 stars to 5 stars and give back the corresponding development materials.