24 cards where the set is “m20” and the cards are exclusive Planeswalker Deck cards

Aggressive Mammoth (Core Set 2020 #337)
Ajani, Inspiring Leader (Core Set 2020 #282)
Celestial Messenger (Core Set 2020 #287)
Chandra, Flame's Fury (Core Set 2020 #294)
Chandra's Flame Wave (Core Set 2020 #295)
Dark Remedy (Core Set 2020 #321)
Ethereal Elk (Core Set 2020 #299)
Gnarlback Rhino (Core Set 2020 #300)
Goldmane Griffin (Core Set 2020 #283)
Impassioned Orator (Core Set 2020 #306)
Mu Yanling, Celestial Wind (Core Set 2020 #286)
Pyroclastic Elemental (Core Set 2020 #296)
Savage Gorger (Core Set 2020 #291)
Savannah Sage (Core Set 2020 #284)
Shivan Dragon (Core Set 2020 #335)
Sorin's Guide (Core Set 2020 #292)
Sorin, Vampire Lord (Core Set 2020 #290)
Thirsting Bloodlord (Core Set 2020 #293)
Twinblade Paladin (Core Set 2020 #285)
Vivien, Nature's Avenger (Core Set 2020 #298)
Vivien's Crocodile (Core Set 2020 #301)
Waterkin Shaman (Core Set 2020 #288)
Wildfire Elemental (Core Set 2020 #297)
Yanling's Harbinger (Core Set 2020 #289)

In the blink of an eye, they strode from deep snow to the end of this search.