Dark Sword has 3 currency - Gold / Soul / Stamina, which is on top of the main game screen.
Gold
The most basic currency acquired for eliminating monsters or selling equipment - Mainly used for strengthening equipment.
Acquired by: Adventure reward / Equipment sale / In-shop purchase
Used for: Strengthening Equipment
Souls
Souls are the most important currency in the Dark world for purchasing equipment or speical potions.
Acquired by: Infinity Tower (3 Souls for every cleared stage) / Friends Invite (30 Souls / invited friend) / In-shop purchase
Used for: Purchasing Gold / Recharging Stamina / Drawing equipment / Purchasing potions
Stamina
1 Stamina is needed to play 1 stage of normal adventure or to play Infinity Tower.
1 Stamina per set period of time is recharged automatically. It can also be purchased in the Shop.
Cooldown time for automatic recharge: 15 mins for Normal mode / 7 mins for Hardcore mode