mtg you can have any number of cards - Simic Emrakul by not a good name Cid, Timeless Artificer (0420) -

Some of the original Magic stories were even based around a quest to find the Black Lotus

Legendary creatures such as Mogis, God of Slaughter or Kaervek the Merciless, which actually appear in the Endless Punishment deck, have been the backbone of previous iterations of red-black group slug decks, and senior game designer Daniel Holt leaned on that archetype history to help shape Endless Punishment

As per yesterday's official MTG Arena Announcements article, these six Explorer decks represent some of the most competitive in the format, and will be available for purchase with gems, MTGA's premium currency

I see it being much more widely used as a card in the main deck, however