After a Unit has been trained it can also be leveled. All eras from classical to modern provide +2 levels. Meaning your unit will be locked at a maximum level based on the era your civ is in.
The max level for a Unit is level 10. For each level, the Unit gains you can apply a Promotion (listed below). These promotions are used to strengthen your unit and give it special abilities.
Every Unit has a preferable Strategic Goodie. If these Goodies are not used then the cost will be increased.
| Unit | Strategic Good |
|---|---|
| Civilian | N/A |
| Settler | N/A |
| Warrior | Silver |
| Hoplite | Titanium |
| Archer | Linen |
| Engineer | Sulphur |
| Lumberjack | Seaweed |
| Miner | Gypsum |
| Explorer | Black pearls |
The cost of promoting your Unit scales up.
When using the Units Preferable Strategic Goodie the cost of upgrading a Unit is: (Current Unit level^2) * 12
If you have the Cheaper Unit Policy the cost of Strategic Goodies goes down by 20%
If you are not using the Preferable Goodie then the cost gets increased by 50%
The Hammer cost of promoting a Unit is 3000 * (1.7)^Current Unit level.
The Growth cost of promoting a Unit is 3000 * (1.7)^Current Unit level.