Finnair is offering a 15% discount on business class fares when paying using American Express card. Also, residents of China, Germany, Hong Kong, Japan, Netherlands, Sweden, United Kingdom and United States will get an upgrade to Finnair Plus Silver status just after one return trip. Finnair Plus Silver status is equivalent of Oneworld Ruby. You need to register for this offer.
There are quite a few good business class offers from the countries where this offer is valid to Asia. Finnair is trying to fill their planes to Asia and apparently the business class demand must be somewhat soft at the moment. Recently SAS was offering status matches to their Eurobonus Gold status for residents of China and Hong Kong.
You can fly Stockholm to Narita and back in Finnair’s business class for about $3.4K. The price is most likely even cheaper during better sales and/or other destinations.
This offer sounds quite good but it is not that great after all. The Silver Finnair Plus status would require 40000 Finnair Plus points (kilometers) and the route above would earn 39848 points by itself. Of course other closer destinations than Tokyo would earn less.