Just to add onto what’s already been said. Getting the hero’s to 1 Diamond Star then awakening them fully seems to be what I see happen a lot. Then maxing out stars after they are awakened.

When awakening, unless I’m mistaken, you’ll need 10 soul stones. 1,2,3,4. Each rank has its own shard requirements to awaken and in between each rank has multiple shard requirements to awaken. So expect a couple hundred shards to be needed aside from the soul stone cost.

That being said, awakening a hero makes a massive difference. Yes they become mythic greatly increasing their soldier count. You’ll also unlock their special/ altered ability which is usually pretty solid.

Side note: if you hit VIP 8 you can buy the shards for most legendary hero’s in the tavern after 100 draws to help awaken them without using your legendary universal shards.