Gold: Earned primarily by clearing stages. Can also be purchased from the store.  Mainly used for upgrading your heroes and buying some store items!

Diamonds: Can be earned from Quests, first time stage clears, the store, and more.  Mainly used for making purchases in the store for chests, shards and refilling your energy.

Tower Tokens: Earned by clearing stages in the Towers (unlock at player level 10).  They’re spent in the Tower tab of the store to purchase various items.

Clan Tokens: Earned by donating runes to your clan members when they request them.  They’re spent in the Clan tab of the store to purchase various items.

Time Stones: Earned by leveling up, some stage clears, autobattles, and the store. They're used to run an autobattle of a previously completed stage.