You can buy items in the store. These items range from free seasonal chests to loot chests and potion chests. You can also buy "Platinum" from the store, which is EA's (the publisher) form of micro-transactions in the game.
Small Chest: 270 Gold
- Contains 1 Random Loot item and 2 Potions.
Medium Chest: 725 Gold -or- 150 Platinum
- Contains 3 Random Loot items and 3 Potions.
Large Chest: 1200 Gold -or- 250 Platinum
- Contains 5 Random Loot item and 5 Potions.