If I have my opponent's Overwhelming Chaos in my hand, can I play Heaven's Blessing and then my opponent's Overwhelming Chaos to force him to pay a bunch of gold since he owns the Strategy?
Heaven's Blessing and card ownership
A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
You can't force him to pay a cost against his will. Your opponent is free to decide whether to pay the gold and draw the cards, or not pay the gold (and not draw the cards), or pay some (and draw some). Of course, if he chooses not to pay, his hand will probably be severely diminished as a result...