Overview
In the Armory you can level up and evolve your troops, in order to gain more power and increase Troops stats. It can be found on the left of your city, near the sea.
To unlock the Armory you need to be able to train Minotaurs.
The Armory has 2 section: Troop Upgrade and Troop Evolution.
Troop Upgrade
In this section you will rise the level of some specific troops. By doing so, your troops base stats will increase. Not every troop can be upgraded, but sometimes the list of upgradable troops is updated with a new troop. The maximum level is 15 or 20, depending on the troop. The higher le troop level, the longer the upgrade process will be. At first you need to select a troop to upgrade, be sure to have the right amount of its upgrading item and enough gold. Then, you have to click "Enhance" to take a spin on the Elixi Wheel, that will stop on a number. That number will be added to the sphere, rising its elixir level. If the wheel stops on Level Up, the troop's level will immeditelly increase. If the sphere is full, you'll get an automatic Level Up on the next spin. Unfortunatelly, the amount of points needed to level up a troop and the probability of getting a Level Up is unknown, since the game doesn't tell you. However, it is said that the best method to get a level up is to fill more than 1/3 of the shere and then stop enhancing that troop for 1-4 weeks. This should give you a boosted proability of getting a Level Up. Take these words with a pinch of salt because it is just an empirical theory.
You can use an Elixir Multiplier to obtain more points. If you get a Level Up while using an Elixir Multiplier, it won't have any additional effect. You could also use a Master's Potion to get a guarantee Level Up.
The upgrading items consists in octagonal stones, with a precious inside. To spin you need as much stones as the current troop level +1. You can perform 1, 5 or 10 enhancment at the time. You can speed up the upgrading process by selecting the 10 enhancment option, and when the wheel start spinning, click the castle icon on the top left of the screen to return to the city view. This will skip the animation but still get you the point and power of the spin.
If you need to know the name of the stone you need to upgrade a specific troop, you can find it in the Upgrade section of each troop page.
Troop Evolution
In the troop evolution section you will power up your troops by evolving their elemental attributes and Life. Use the 10 units of Elder Fossil or Twilight Fossil (depend on the troop) to refine the troop. Each time, the level of every bar will increase or decrese randomly. After you refine, you can choose whether to accept the result or not. Depending on the accepted result, your power may increase or decrease. You can also use the appropriate Relic to greatly boost the results when refining. Once every bar is filled, you can evolve the troop to the next level using Phantom Potions or Orale Potions (depend on the troop). You need the same amount of potion as your troop's current evolution level to unlock the next one. To know the fossil needed to refine a troop, visit the Evolution section on its page