Skirmish
These doctrines have a wide engagement range and can typically be used in any situation. They are widely available on contract, and are fairly cheap and effective.
Strategic
These doctrines are more advanced, and require additional support (e.g capitals) and knowledge to utilize properly. Due to their cost, they are less abundant on contracts.
Specialized
These doctrines have a specific use case, and are only used in situations where they’re the right tool for the job. They are commonly deployed by special interest groups. Certain doctrines (e.g tornados) will be available on contract.
