Buildings

Buildings are your main source of gold in the game, barring a few that server other purposes.

The Arena and Fusion Master cannot be sold, the others can for 20% of the purchase price regardless of upgrades. All buildings can be moved around and flipped in two directions, there is no need to sell buildings to rebuild them elsewhere.

Fusion Master
Cost: Free

Upgrades: None

Allows you to fuse and enhance armor.

Arena
Allows you to join PvP tournaments once you hit level 10.

Cost: Free

Upgrades: None

Armorsmith
Cost: Increases with each additional Armorsmith Upgrades:
 * 1st :
 * 2nd :
 * 3rd : 25,000 gold
 * 4th :
 * 5th :
 * 6th :
 * Level 2 : 10,000 gold; 5% less crafting Armor Sets
 * Level 3 :

Income Buildings
Each building produces gold at different rates, and once their storage is full they will stop generating gold until emptied. You can collect gold by clicking on the bag icon hovering over the building (which appears at about 25% capacity), or click on the building and collect from there. Gold bars will pop out, which you can click again to collect. (This last bit is not necessary, gold bars will start to expire after 10 seconds, but will be added to your balance once gone. It just speeds up collecting.)

Upgrades increase storage size, while keeping the time to fill up the same, resulting in a higher gold gain per hour.

Fountain
Cost: 100 gold

Income: 600 gold/hour

Storage: 50 gold

Upgrades:
 * Level 2 : 200 gold; increases storage to 75 gold, income to 900 gold/hour
 * Level 3:  3 gems; increases storage to 125 gold, income to 1200 gold/hour

Guard Tower
Cost: 300 gold

Income: 167 gold/hour

Storage: 2,000 gold

Upgrades:
 * Level 2 :
 * Level 3 : 5 gems; increases storage to 3,300 gold, income to ? gold/hour

Cathedral
Cost: 1,000 gold

Income: 500 gold/hour

Storage: 500 gold

Upgrades:
 * Level 2 :
 * Level 3 : 10 gems; increases storage to 800 gold, income to ? gold/hour

Tavern
Cost: 7,500 gold

Income: 475 gold/hour

Storage: 1,900 gold

Upgrades:
 * Level 2 :
 * Level 3 : 15 gems; increases storage to 3,000 gold, income to ? gold/hour

Crystal Conservatory
Cost: 15,000 gold

Income: 800 gold/hour

Storage: 400 gold

Upgrades:
 * Level 2 :
 * Level 3 : 20 gems; increases storage to 600 gold, income to ? gold/hour

Dungeon
Cost: 30,000 gold

Income: 450 gold/hour

Storage: 9,000 gold

Upgrades:
 * Level 2 : 20,000 gold; increases storage to 10,500 gold, income to 510 gold/hour
 * Level 3 : 30 gems; increases storage to 15,000 gold, income to ? gold/hour

Training Field
Cost: 50,000 gold

Income: 1,167 gold/hour

Storage: 14,000 gold

Upgrades:
 * Level 2 :
 * Level 3 :

Monster Nest
Cost: 100,000 gold

Income: 750 gold/hour

Storage: 1,500 gold

Upgrades:
 * Level 2 :
 * Level 3 :