coronation_hof_visit_effect

coronation_hof_visit_effect = {
	involved_activity = {
		add_activity_log_entry = {
			key = activity_hof_arrival_log
			tags = { good }
			score = 20
			character = activity_host
			target = scope:hof
		}
		# Small boost to Magnificence
		activity_special_type_progression_tiny = yes
		custom_tooltip = coronation_tt_positive_tiny
		activity_host = {
			# Hosts get a bit of legitimacy and piety from having the HoF show up
			add_legitimacy_effect = { LEGITIMACY = minor_legitimacy_gain }
			add_piety = minor_piety_gain
		}
		activity_location = {
			show_as_tooltip = {
				add_province_modifier = {
					modifier = ach_hof_visit_modifier
					years = 10
				}
			}
			if = { # Add the Papal visit modifier
				limit = {
					NOT = { has_province_modifier = ach_hof_visit_modifier }
				}
				hidden_effect = {
					add_province_modifier = {
						modifier = ach_hof_visit_modifier
						years = 10
					}

					# Toast the divine trinity of those who care: the host, the local baron and the holy count
					scope:host = {
						send_interface_toast = {
							title = ach_coronation.0001.tt.hof_visit.title
							left_icon = scope:hof
							custom_tooltip = ach_coronation.0001.tt.hof_visit
						}
					}
				}
			}
		}
	}
}

As written in game/common/scripted_effects/10_ach_effects.txt.