Special

A Magic card may have the special rarity.
These are marked as common but have an "S" instead of a "C" in the information below the text box. Like basic lands, cards with this rarity are always available to you, whether you drafted it or not.
The special rarity was formally introduced for <c>The Prismatic Piper</c> in Commander Legends. It was later joined by <c>Faceless One</c> in Commander Legends: Battle for Baldur's Gate, which had a similar function. 
The S rarity is also present on cards in Kaladesh Inventions, Amonkhet Invocations, and Ultimate Masters/Ultimate Box Toppers, but in this case it signifies that they are of a higher rarity than mythic rare.
==References==