Just as I felt Innistrad had the opportunity to mechanically define what a Werewolf was, Dominaria was going to be able to do the same with a story

Absorbing Man and Titania Angel of Destiny Angrath's Marauders Anthem of Rakdos Approach My Molten Realm Aragorn, Hornburg Hero Armament of Nyx Assault Strobe Aven Sunstriker Battle Mastery Bitter Feud Black Panther, Hope Enduring Blind Fury Bonescythe Sliver Boros Charm Boros Keyrune Boros Swiftblade Bushi Tenderfoot Bushi Tenderfoot Calamity Bearer Casey Jones, Asphalt Hooligan Celestial Mantle Chandra's Pyreling Charging Tuskodon Choose Your Weapon Cleaver Riot Cloud, Planet's Champion Collective Inferno Crimson Caravaneer Curse of Bloodletting Desperate Gambit Dictate of the Twin Gods Disciplined Duelist Double Cleave Double Deal Dragon Tyrant Dragonclaw Strike Drogskol Reaver Dual Doomsuits Efreet Flamepainter Favored of Iroas Fencing Ace Fiendish Duo Fire Servant Fireshrieker Furnace of Rath Fury Game of Chaos Ghostblade Eidolon Gimli of the Glittering Caves Gisela, Blade of Goldnight Goblin Charbelcher Goblin Goliath Goldnight Castigator Gratuitous Violence Hearthfire Hobgoblin Holy Avenger Human Torch Impulsive Maneuvers Inquisitor's Flail Insult // Injury Insult // Injury Iroas's Champion Jawbone Duelist Jenny, Generated Anomaly Kellan, Planar Trailblazer Kor Duelist Leonardo, Worldly Warrior Lightning, Army of One Loot, the Pathfinder Lyzolda, the Blood Witch Avatar Markov Blademaster

You don't choose a target for Yuna's Whistle at the time you cast it
As far as Universes Beyond crossovers go, I think these cards represent both the current apex, and a potentially historic turning point
There is no set in the history of the Pokmon TCG where it is not a significant card, and Expedition is no exception