send_slain_combatant_message

send_slain_combatant_message = {
	# The positioning of the character portraits needs to sync up with the loc-string we're using.
	if = {
		limit = {
			$IS_ENEMY_MESSAGE$ = no
		}
		root = {
			save_scope_as = right_character
		}
		$KILLER$ = {
			save_scope_as = left_character
		}
	}
	else = {
		root = {
			save_scope_as = left_character
		}
		$KILLER$ = {
			save_scope_as = right_character
		}
	}

	# Send either a toast or a message to this character, depending on what variable was passed in.
	if = {
		limit = {
			$TOAST$ = yes
		}
		send_interface_toast = {
			message_filter_type = combat_casualties
			title =  $DESC$
			left_icon = scope:left_character
			right_icon = scope:right_character
		}
	}
	#
	else_if = {
		limit = {
			$IS_ENEMY_MESSAGE$ = no
		}
		send_interface_message = {
			type = event_slain_combatants_good
			title = $TITLE$
			desc = $DESC$
			left_icon = scope:left_character
			right_icon = scope:right_character
		}
	}
	else = {
		send_interface_message = {
			type = event_slain_combatants_bad
			title = $TITLE$
			desc = $DESC$
			left_icon = scope:left_character
			right_icon = scope:right_character
		}
	}
}

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