Specifically, the Elsa, Snow Queen promo card released at D23 Expo, Disneys annual convention, quickly rocketed to become one of the most valuable Lorcana cards even ahead of the card games full release
doi:10.1257/aer.89.5.1063
So, when you build a reasonable collection of pocket monsters (it won't take you long, considering the number of free cards the game throws at you in the first hours of gameplay), you can take them into battle
Also similar to lands, one of the big reasons that Commander 2018 was so poorly received is that the decks were severely lacking in good colorless cards (in fact, for half of the 2018 decks, the only colorless card worth mentioning was Sol Ring, which has been in every Commander deck since the start of the series)
Ursula combos with any Song that costs three or less (ok maybe not ANY, sorry Reflection), but Bibbidi Bobbidi Boo and Mother Knows Best are both within Emerald, her starting color, so I expect them to see the most play overall
This may not sound too strong, but time and time again, one simple mana can be all you need to win a game or comeback from a rough situation, and nearly every Commander deck needs a Command Tower