Camps
Camps have a level from 1 to 4. Level 1 camps are easy and are a good first target. Higher levels have more guards and more resources.
Camps of the same level differ in size. A few are rich: more guards, more loot.
How strong?
At first you do not know how strong the guards of a camp are: the map shows a "?". Send spies, or attack the camp once, and from then on you see its strength.
Rewards
When you win, your soldiers bring the camp's resources home. After a few hours the camp has new guards and new resources.
Enemies
Rust Bug: attack 15, defense 25.
Rust Robot: attack 40, defense 70.
Rust Giant: attack 120, defense 250.
Out of the camps
The Rust does not always stay in its camps.