I'm surprised how many people seem to not have even heard of Swaziland. I mean I don't know much about it, but I had certainly heard of it.
Also, though they may not keep patents online, it's quite likely they do keep them in a computerized database for logistical purposes. And just for those curious, it's possible to copyright creative works in Swaziland and have them protected in 160+ other member nations with a single form. Realistically this probably means that Blizzard could have filed with any of those nations and chose to have it protected in any of the others, or to protect it in just the filing nation, or in just a small selection of the nations.
Basically, we'd need to look through all possible countries (which is around 196, but it depends on the source - it's above 190 in almost all cases). It's probably easier to look through countries that store copyrights online for obvious reasons. I'm not sure if you'd be able to get much out of offices that don't have online copyright records due to obvious reasons.
Who we really want to be looking at are their legal reps. You won't get anything out of them directly of course, but they may have left a paper trail to follow. It's unlikely, but still, might be worth a shot.
Also, amusingly, the patent after the Hearthstone one (i.e. #86003647) is for something called B.I.L.F.
Blizzard, I'd like to... you know the rest
It used to go F&F Alpha, then invite only Beta.