journey_knowledge_hoarding_skill_effect

journey_knowledge_hoarding_skill_effect = {
	scope:activity = {
		if = {
			limit = { has_variable = skill_chance }
			change_variable = {
				name = skill_chance
				add = $VALUE$
			}
		}
		else = {
			set_variable = {
				name = skill_chance
				value = $VALUE$
			}
		}
		if = {
			limit = {
				$VALUE$ == 25
			}
			custom_tooltip = increase_skill_chance_25
		}
		if = {
			limit = {
				$VALUE$ == 20
			}
			custom_tooltip = increase_skill_chance_20
		}
		else_if = {
			limit = {
				$VALUE$ == 15
			}
			custom_tooltip = increase_skill_chance_15
		}
		else_if = {
			limit = {
				$VALUE$ == 10
			}
			custom_tooltip = increase_skill_chance_10
		}
		else_if = {
			limit = {
				$VALUE$ == 5
			}
			custom_tooltip = increase_skill_chance_5
		}
		else_if = {
			limit = {
				$VALUE$ == 30
			}
			custom_tooltip = increase_skill_chance_30
		}
		else_if = {
			limit = {
				$VALUE$ == 35
			}
			custom_tooltip = increase_skill_chance_35
		}
		else_if = {
			limit = {
				$VALUE$ == 50
			}
			custom_tooltip = increase_skill_chance_50
		}
		else_if = {
			limit = {
				$VALUE$ == 2
			}
			custom_tooltip = increase_skill_chance_2
		}
		if = {
			limit = {
				has_variable = skill_chance
				var:skill_chance > 100
			}
			set_variable = {
				name = skill_chance
				value = 100
			}
		}
	}
}

As written in game/common/scripted_effects/00_journey_effects.txt.