This sort of has two modes, and you can access both at the same time
Those 15 cards need to get you through 1 or 2 games against all the weird and zany decks you might encounter in the Modern wilderness (a wild Ad Nauseam/Humans/Dredgevine/Norin the Wary appeared!)
Each Set Booster contains 12 Magic cards, 1 Art Card, and 1 token, ad card, Helper card, or special card from Magic's history (a card from "The List")
The artwork differs here with Elsa shown in a more traditional 'let it go' style pose, in contrast with the design of her firing ice at a lake, causing fish to be thrown into the air, which is depicted in the Archazia's Island set
So this will be just fine in Commander, but I dont think this will get there fast enough in 60-card formats
It was a more subtle change, adding some more (non-game related) information on the bottom of the card, which received a black colored background