Banned and restricted
Every card belonging a Modern-legal set except those underneath are legal in Modern Duel Commander. A Modern-legal set is a standard set published after the Eighth Edition (included) and Modern Horizon sets.
Our goal is to ban as few cards as possible, and let the players enjoy their cards in a high power format. This format is based on the singleton rule, and as such is already subject to a lot of variance. If a deck appears to be too strong, our goal is to first let the players try to react to it. Then, if adaptation is not possible, or too costly to have a chance against the other archetypes of the format, we will consider banning the card causing that issue.
That is why we will focus mainly on cards that provide extremely repetitive, unenjoyable gameplay patterns, and/or are extremely hard to interact with through standard means.
We reserve the right to ban cards for other reasons however. For instance, cards that are not suited for the specific rules of this format, or cards that may cause troubles for tournament organization.
Bans are not based on statistics or results only (since those are extremely parse and are likely to remain as such for a long time), but a lot on our experience with the cards and talks with players.
Current banned cards as commander only
Those cards are banned as a commander only. It means you can still play them in your deck, they just can't be chosen as your commander.
Current banned cards as companion only
Those cards are banned as a companion only. It means you can still play them in your deck, they just can't be chosen as your companion.