flygon pokemon card - GX 110/236 Colorless Sand Tomb (110) The Defending Pokémon cant retreat during your opponents next turn Flygon - 101/094

theyre only legal in whichever Constructed format theyre already legal for

This can ultimately allow the player to potentially find a vital card that's necessary to win the game, whether through reducing the opponent's deck size, healing their Pokmon's health, or in Charizard's case, finding more Leon cards to discard to increase the damage output from Royal Blaze

The long answer is naturally more complicated

Barbarians

Released just last year in the Duskmourn MTG set, Overlord of the Boilerbilges has always been one of the cheapest Overlords, not finding its way into the 4-color Zur the Enchanter Standard deck that was pretty popular before Beanstalk got banned (check our MTG Arena decks guide for more details)

Such an ability triggers whenever an instant or sorcery spell that player controls whose gift cost was paid resolves