valid_for_feud_events_with_target_trigger

valid_for_feud_events_with_target_trigger = {
	# General checks
	valid_for_feud_events_trigger = yes
	# Victim House Head must exist
	exists = $TARGET$.house.house_head
	# Target House must be different
	NOT = { house = $TARGET$.house }
	# Ensure target is 'equal'
	trigger_if = {
		limit = {
			is_landed = yes
			$TARGET$.house.house_head = { is_landed = yes }
		}
		tier_difference = {
			target = $TARGET$.house.house_head
			value >= -1
		}
		tier_difference = {
			target = $TARGET$.house.house_head
			value <= 1
		}
	}
	trigger_else = {
		NOR = {
			highest_held_title_tier > tier_duchy
			$TARGET$.house.house_head.highest_held_title_tier > tier_duchy
		}
	}
	NOR = {
		# Is not part of same family as target House Head
		is_close_family_of = $TARGET$.house.house_head
		# Is not friendly with target House Head
		has_any_good_relationship_with_character_trigger = { CHARACTER = $TARGET$.house.house_head }
	}
	# Avoid starting Feuds between Vassals and Lieges, as they are not 'equals'
	trigger_if = {
		limit = { exists = $TARGET$.house.house_head.liege }
		NOR = {
			# Is not liege of target House Head
			this = $TARGET$.house.house_head.liege
			# Does not share house with target's liege
			this.house = $TARGET$.house.house_head.liege.house
		}
	}
	# Must be near target House Head
	in_diplomatic_range = $TARGET$.house.house_head
	# Save scopes for checking against
	save_temporary_scope_as = house_head_temp
	$TARGET$.house.house_head = { save_temporary_scope_as = target_house_head_temp }
}

As written in game/common/scripted_triggers/03_bp1_scripted_triggers.txt.