If you were looking to expand your Gwent collection, now would be a very good time to do so as all card kegs opened until Monday (April 23rd, 12 PM CEST) will have a guaranteed premium (animated) card. More importantly, the premium card will occupy the 5th slot in the keg, meaning you will be able to choose which one out of three premium cards you'll add to your collection.
It is also worth mentioning that this promotion isn't exclusive to paid card kegs. As such, if you have a whole bunch of ore laying around, you can now convert it into highly valuable and rather fancy premium cards. Not a bad deal, not a bad deal at all!
Before you go and spend any money, however, I would just like to make sure you know that Gwent is currently on a six month hiatus as CDPR works on the absolutely massive Homecoming update. You can find all of the details over here, but the important takeaway is that there won't be any major content or balance changes for the foreseeable future. As such, do consider whether you're going to be invested in Gwent long term as the current version is unlikely to keep you occupied for the half of year CDPR will need to release Homecoming.
With that little bit of warning now out of the way, I wish you the best of luck with your kegs!