Emerald cards in Rise of the Floodborn, the latest set for Disney Lorcana, are typically for those players who enjoy mischief and messing with their opponents
Spoilers, they're both running the backbreaking Grief scam strategy that has plagued Modern ever since Modern Horizons 2 came out - for anyone not aware, that's evoking Grief, then playing Ephemerate or Malakir Rebirth to bring it back and get two copies of the card-stealing trigger, plus a relevant creature, all for just one mana
However, as it has an enter the battlefield trigger that causes each opponent to discard a card, this lets it function similarly to a sorcery the first time it is cast
Special Summon this card from your hand, then if you control no other monsters, you can destroy 1 monster on the field with the highest ATK (your choice, if tied)