25 cards where the set is “m19” and the cards are exclusive Planeswalker Deck cards

Aggressive Mammoth (Core Set 2019 #302)
Ajani's Influence (Core Set 2019 #282)
Ajani, Wise Counselor (Core Set 2019 #281)
Arisen Gorgon (Core Set 2019 #292)
Court Cleric (Core Set 2019 #283)
Gravewaker (Core Set 2019 #293)
Kargan Dragonrider (Core Set 2019 #297)
Liliana's Spoils (Core Set 2019 #294)
Liliana, the Necromancer (Core Set 2019 #291)
Pendulum of Patterns (Core Set 2019 #288)
Riddlemaster Sphinx (Core Set 2019 #287)
Sarkhan, Dragonsoul (Core Set 2019 #296)
Sarkhan's Dragonfire (Core Set 2019 #298)
Sarkhan's Whelp (Core Set 2019 #299)
Serra's Guardian (Core Set 2019 #284)
Shivan Dragon (Core Set 2019 #300)
Silverbeak Griffin (Core Set 2019 #285)
Skalla Wolf (Core Set 2019 #303)
Tattered Mummy (Core Set 2019 #295)
Tezzeret, Cruel Machinist (Core Set 2019 #286)
Tezzeret's Gatebreaker (Core Set 2019 #289)
Tezzeret's Strider (Core Set 2019 #290)
Ursine Champion (Core Set 2019 #304)
Vivien of the Arkbow (Core Set 2019 #301)
Vivien's Jaguar (Core Set 2019 #305)

Though this query has ended, its relics still slumber in New Argive.