friendly_counsel_skill_gain_effect

friendly_counsel_skill_gain_effect = {
	if = {
		limit = {
			has_perk = friendly_counsel_perk
		}
		if = {
			limit = {
				NOT = { has_variable = current_friendly_counsel_perk_value }
			}
			set_variable = {
				name = current_friendly_counsel_perk_value
				value = 0
			}
		}

		every_relation = {
			type = friend
			add_to_temporary_list = friendly_counsel_friends
		}
		every_relation = {
			type = best_friend
			add_to_temporary_list = friendly_counsel_friends
		}
		every_relation = {
			type = blood_brother
			add_to_temporary_list = friendly_counsel_friends
		}

		if = {
			limit = {
				exists = var:current_friendly_counsel_perk_value
				save_temporary_scope_as = affected_friend
				OR = {
					var:current_friendly_counsel_perk_value < friendly_counsel_max
					AND = { # If you have a Blood Brother you get one extra skill
						government_has_flag = government_is_nomadic
						var:current_friendly_counsel_perk_value < 6
						any_in_list = {
							list = friendly_counsel_friends
							has_relation_blood_brother = root
						}
					}
				}
				any_in_list = {
					list = friendly_counsel_friends
					count > scope:affected_friend.var:current_friendly_counsel_perk_value
				}
			}
			random_list = {
				1 = {
					add_character_modifier = {
						modifier = friendly_counsel_martial_gain
					}
				}
				1 = {
					add_character_modifier = {
						modifier = friendly_counsel_diplomacy_gain
					}
				}
				1 = {
					add_character_modifier = {
						modifier = friendly_counsel_intrigue_gain
					}
				}
				1 = {
					add_character_modifier = {
						modifier = friendly_counsel_stewardship_gain
					}
				}
				1 = {
					add_character_modifier = {
						modifier = friendly_counsel_learning_gain
					}
				}
			}
			change_variable = {
				name = current_friendly_counsel_perk_value
				add = 1
			}
		}
	}
}

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