With the rotation of Return to Ravnica for Khans of Tarkir, all sanctioned formats as well as the group that oversees the Commander format announced their updates to banned and restricted lists.
The following changes are:
Standard, Modern, Legacy, Vintage
The Rules Committee group has decided to do away with the “Banned as Commander” list and instead use it as a reason for why a card should be banned in the format in general. As a result, the four legends currently in that list had to have their statuses updated. These changes are:
Furthermore Metalworker is unbanned. The reason for that being that while it can be powerful, it’s fragile and requires a deck built around it for it to be useful.
Functional Errata and Relevant Rules Changes
The explanations of the non-Commander Banned & Restricted changes can be found here.
The Commander announcement can be found here.
The full list of rules clarifications can be viewed here.