They talked about it in the town hall around new years
https://peakd.com/hive-13323/@splinterlands/splinterlands-town-hall-summary-january-2nd-2023
They didn't give a whole ton of details but they're talking about rolling it out in the second quarter which starts in like a week, so we may know more soon.
I was taking a look at it and the truth is this part is very interesting, the Runi Combining thing and the promo cards caught my attention, genius!