vcmi/config/skills.json

{
    "estates" : {
        "basic" : {
            "description" : "Hero generates 250 gold each day.",
            "effects" : [
                {
                    "subtype" : 13,
                    "type" : "SECONDARY_SKILL_PREMY",
                    "val" : 250,
                    "valueType" : "BASE_NUMBER"
                }
            ]
        },
        "advanced" : {
            "description" : "Hero generates 500 gold each day.",
            "effects" : [
                {
                    "subtype" : 13,
                    "type" : "SECONDARY_SKILL_PREMY",
                    "val" : 500,
                    "valueType" : "BASE_NUMBER"
                }
            ]
        },
        "expert" : {
            "description" : "Hero generates 1000 gold each day.",
            "effects" : [
                {
                    "subtype" : 13,
                    "type" : "SECONDARY_SKILL_PREMY",
                    "val" : 1000,
                    "valueType" : "BASE_NUMBER"
                }
            ]
        }
    }
}