effect · add_doctrine_cost_reduction

Hands-On Usage

add_doctrine_cost_reduction is commonly used to reward players with a one-time doctrine research cost discount after completing specific focuses, decisions, or events, helping nations rapidly advance through their military doctrine trees. For example, upon completing a "Military Reform" type focus, you might grant players several doctrine price reductions to simulate the historical progression of military doctrine breakthroughs.

# Example focus completion reward block
focus = {
    id = military_doctrine_reform
    ...
    completion_reward = {
        add_doctrine_cost_reduction = {
            name = military_reform_bonus
            cost = 0.5
            uses = 2
            category = land_doctrine
        }
    }
}

Synergy

• [has_completed_focus](/wiki/trigger/has_completed_focus): First verify that the player has completed a prerequisite focus before triggering the discount reward, preventing the discount from taking effect at illogical moments.
• [add_political_power](/wiki/effect/add_political_power): Doctrine research typically consumes political power, so granting it alongside the discount creates a more complete reward package that aligns with design pacing.
• [can_research](/wiki/trigger/can_research): In conditional blocks, verify whether the doctrine category is currently researchable, preventing the discount from being wasted in meaningless states.
• [add_tech_bonus](/wiki/effect/add_tech_bonus): Both are research acceleration effects; combining them covers both the "discount uses" and "research speed bonus" dimensions simultaneously, forming a more comprehensive research reward.

Common Pitfalls

1. Forgetting to specify category or misspelling the field name: This effect typically requires explicitly designating the target doctrine category (such as land_doctrine or naval_doctrine). If the field is missing or misspelled, the discount will not bind correctly to the corresponding doctrine, and the game may not report an error, causing the effect to fail silently.
2. Assuming the effect stacks infinitely: The uses parameter controls how many times the discount can be used. Triggering the same effect multiple times will not merge the uses into a single discount entry. Pay attention to ensuring the uniqueness of trigger conditions; otherwise, players can exploit repeated event triggering to farm large quantities of discount uses.