As a constructed format, Legacy does not rotate and allows cards to be played from all Magic sets (with the exception of those from the banned card list). Your deck and sideboard is not allowed to hold more than four of any individual card in this format, except for basic lands.

• Minimum deck size of 60 cards
• Up to 15 cards in your sideboard (if used)

Wizards Official Page for Legacy: https://magic.wizards.com/en/formats/legacy

Banned & Restricted List: https://magic.wizards.com/en/banned-restricted-list