Sol Ring

Standard	Rotated out on April 19, 1995
Pioneer	Not Legal
Modern	Not Legal
Legacy	Banned since May 1, 1996
Vintage	Restricted since January 25, 1994
Commander	Never Banned
Pauper	Never Banned
Oathbreaker	Banned since June 19, 2018
Extended	Rotated out on October 1, 1999

View on Scryfall

Timeline

• August 5, 1993 - Released
• January 25, 1994 - Status changed to Restricted in Vintage
• January 10, 1995 - Status changed to Restricted in Standard
• April 19, 1995 - Status changed to Rotated in Standard
• May 1, 1996 - Status changed to Banned in Legacy
• July 1, 1997 - Status changed to Banned in Extended
• October 1, 1999 - Status changed to Rotated in Extended
• June 19, 2018 - Status changed to Banned in Oathbreaker

Rationale

Sol Ring is banned or restricted in nearly every format that it would be legal in due to its excessive rate of mana acceleration. It remains fully legal only in Commander, protected by its status as a format-defining card.