Digital-only cards in digital-only formats like Historic give Wizards of the Coast the ability to functionally rebalance cards simply and clearly. They can simply update the text digitally, and the cards will remain accurate to their new function.
Functional rebalancing is a significant change in how formats are balanced. Going forward, WotC will be managing formats on MTG Arena in two different ways. "Print" formats, like Standard, will continue to work exactly like they do in tabletop Magic. For "Live" formats, like Historic, balancing is added alongside banning and suspension as a tool to address problems and make improvements to the format.
Currently, WotC is restricting these changes to digital-only cards, where there will be no conflict between a digital and printed version of a card. They are working on expanding beyond this (for example, by rebalancing previously banned cards so they can be safely returned to play in digital formats only).
A more serious and permanent version was during the October 2021 Ban and Restricted List Update, when five designed-for-digital cards from Jumpstart: Historic Horizons were updated. The most critical change was shutting the loop created by Vesperlark and perpetual toughness shrinkers; other assorted positive effects were also added.
List of Rebalanced cards
|Card||Date of change||Original||Changed to||Reason|
|Davriel's Withering||2021-10-03||Target creature perpetually gets -1/-2.||Target creature an opponent controls perpetually gets -1/-2.||To prevent an undesirable combo with Vesperlark that can result in a drawn game.|
|Davriel, Soul Broker||2021-10-03||-3: Target creature perpetually gets -3/-3.||-3: Target creature an opponent controls perpetually gets -3/-3.||To prevent an undesirable combo with Vesperlark that can result in a drawn game.|
|Faceless Agent||2021-10-03||Power/Toughness: 2/1||Power/Toughness: 2/2||Making it better|
|Sarkhan, Wanderer to Shiv||2021-10-03||0: Conjure a Shivan Dragon card into your hand.||+1: Conjure a Shivan Dragon card into your hand.||Making it better|
|Subversive Acolyte||2021-10-03||Mana cost
[...] becomes a Human Cleric. It gets +1/+2 [...]
[...]becomes a Phyrexian. It gets +3/+3 [...]
[...] becomes a Human Cleric. It gets +1/+1 [...]
[...]becomes a Phyrexian. It gets +3/+2 [...]
|Making it better|
- Jay Parker & Donald Smith (October 13, 2021). "October 13, 2021 Banned and Resticted Announcement". magicthegathering.com. Wizards of the Coast.
- Adam Styborski (May 6, 2021). "Welcome to the Summer of Legend". magicthegathering.com. Wizards of the Coast.
- Wizards of the Coast (June 30, 2021). "MTG Arena Announcements". magicthegathering.com. Wizards of the Coast.