I made a mistake while writing the patch notes for version 640: The patch notes stated the wrong end date (February 16th) for the full refund of golems and knights with life leech, while it was correctly displayed in-game (February 12th).
Arcanox Version 642 extends the refund period to February 17th, 07:00:00 (UTC).
It is available on Google Play.
During a refund period the affected cards are not offered by the bazaar and can not be acquired through cards packs. This means no one can exploit them to gain more Mana than usual from cards packs or the bazaar.
Sorry for the inconvenience,
Hint: When Google Play doesn’t show the update either restart your device or force-stop the Google Play app to clear it’s cache. Do NOT uninstall Arcanox, because this deletes the local save files!