In Urza's Saga , they showed up on Wizard Mentor
Take just shy of 30 Apostles, drop in a Razaketh, the Foulblooded, a toolbox of demons like Lord of the Void, Archfiend of Depravity, and other cards that sound like Slayer albums from the 80s, and go to town
The first card was given out with the purchase of a movie ticket for Pokmon: The Movie 2000, Ancient Mew graded by CGC Near Mint+ 7.5

On Sale 5/6 AMAZING SPIDER-MAN #28 MAGIC: THE GATHERING VARIANT COVER BY ROBERTA INGRANATA 75960621001502841 AMAZING SPIDER-MAN #28 MAGIC: THE GATHERING VIRGIN VARIANT COVER BY ROBERTA INGRANATA 75960621001502818 CIVIL WAR: UNMASKED #1 MAGIC: THE GATHERING VARIANT COVER BY PAOLO RIVERA 75960621471600151 CIVIL WAR: UNMASKED #1 MAGIC: THE GATHERING VIRGIN VARIANT COVER BY PAOLO RIVERA 75960621471600118 IRON MAN #5 MAGIC: THE GATHERING VARIANT COVER BY KEVIN GLINT 75960621491400551 IRON MAN #5 MAGIC: THE GATHERING VIRGIN VARIANT COVER BY KEVIN GLINT 75960621491400517 MARC SPECTOR: MOON KNIGHT #4 MAGIC: THE GATHERING VARIANT COVER BY CHRIS BACHALO 75960621496900431 MARC SPECTOR: MOON KNIGHT #4 MAGIC: THE GATHERING VIRGIN VARIANT COVER BY CHRIS BACHALO 75960621496900417 X-MEN #29 MAGIC: THE GATHERING VARIANT COVER BY LIE SETIAWAN 75960620920002951 X-MEN #29 MAGIC: THE GATHERING VIRGIN VARIANT COVER BY LIE SETIAWAN 75960620920002917 On Sale 5/13 AMAZING SPIDER-MAN/VENOM: DEATH SPIRAL - BODY COUNT #1 MAGIC: THE GATHERING VARIANT COVER BY LUCIO PARRILLO 75960621648200151 AMAZING SPIDER-MAN/VENOM: DEATH SPIRAL - BODY COUNT #1 MAGIC: THE GATHERING VIRGIN VARIANT COVER BY LUCIO PARRILLO 75960621648200118 BLACK CAT #10 MAGIC: THE GATHERING VARIANT COVER BY ALESSANDRA PISANO 75960621252101031 BLACK CAT #10 MAGIC: THE GATHERING VIRGIN VARIANT COVER BY ALESSANDRA PISANO 75960621252101016 CAPTAIN AMERICA #11 MAGIC: THE GATHERING VARIANT COVER BY E.M

They can affect the Pokmon with the ability, other Pokmon in play, or the game itself
Example Gallery: Spider-Man vs