unite_the_western_slavs_decision_effects

unite_the_western_slavs_decision_effects = {
	#Prestige
	add_prestige = massive_prestige_gain

	#Innovations
	culture = {
		add_random_innovation = culture_group_military
		add_random_innovation = culture_group_civic
	}

	#Laws
	if = {
		limit = { has_realm_law = crown_authority_0 }
		add_realm_law_skip_effects = crown_authority_2
	}
	else_if = {
		limit = {
			OR = {
				has_realm_law = crown_authority_1
				has_realm_law = crown_authority_2
			}
		}
		add_realm_law_skip_effects = crown_authority_3
	}

	#Handle de jure drift & destructions of other kingdom titles
	title:k_poland = { add_to_list = west_slavic_kingdoms }
	title:k_pomerania = { add_to_list = west_slavic_kingdoms }
	title:k_bohemia = { add_to_list = west_slavic_kingdoms }
	title:k_sorbia = { add_to_list = west_slavic_kingdoms }
	title:k_moravia = { add_to_list = west_slavic_kingdoms }

	if = {
		limit = { highest_held_title_tier = tier_kingdom }
		custom_tooltip = unite_the_western_slavs_decision_titles_tt
	}
	custom_tooltip = unite_the_western_slavs_decision_titles_empire_tt
	# If Saxony has been created, shift everything back into Polabia
	if = {
		limit = {
			is_target_in_global_variable_list = {
				name = unavailable_unique_decisions
				target = flag:flag_formed_saxony
			}
		}
		title:k_saxony = {
			every_in_de_jure_hierarchy = {
				limit = { tier = tier_duchy }
				set_de_jure_liege_title = title:k_sorbia
			}
		}
	}
	hidden_effect = {
		every_duchy = {
			limit = {
				title_capital_county.title_province ?= {
					geographical_region = custom_west_slavia
				}
				kingdom ?= {
					NOR = {
						this = title:k_poland
						this = title:k_pomerania
						this = title:k_bohemia
						this = title:k_moravia
						this = title:k_sorbia
					}
				}
			}
			set_de_jure_liege_title = title:k_sorbia
		}
		scope:western_slav_uniter = {
			#If king-tier, give them the West-Slavia title
			if = {
				limit = { highest_held_title_tier = tier_kingdom }
				create_title_and_vassal_change = {
					type = created
					save_scope_as = title_change
					add_claim_on_loss = no
				}
				title:e_west_slavia = {
					change_title_holder = {
						holder = scope:western_slav_uniter
						change = scope:title_change
					}
				}
				resolve_title_and_vassal_change = scope:title_change
			}
			# Drift kingdoms to empire
			every_in_list = {
				list = west_slavic_kingdoms
				set_de_jure_liege_title = scope:western_slav_uniter.primary_title
			}
		}
	}
}

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