There are currently 21 different units to choose from to make up your army. The default look of all the units depends on the party picked at the beginning of the game. These units' looks can be customized as well personally, or downloaded from the Market, where you can find many skins made by other people who play the game. You can also publish your own customized skin on the market too.
You need mythril to upgrade your units and making them more efficient.
The list includes:
Unlocked at Player Level 1
Unlocked at Player Level 2
Unlocked at Player Level 3
Unlocked at Player Level 4
Unlocked at Player Level 5
Unlocked at Player Level 6
Unlocked at Player Level 7
Unlocked at Player Level 8
Unlocked at Player Level 9
Unlocked at Player Level 10
Unlocked at Player Level 11
Unlocked at Player Level 12
All items (22)