​4 CMC commander, also referred to as just 4 CMC, is an alternative sub format to Commander adding the restriction of only allowing non-land cards with a converted mana cost 4 or greater. This refers to the actual casting cost of the spell. For example the card Fire//Ice has a total converted mana cost of 4 as a split card, but the individual spells cost 2 mana, therefore are not legal. This restriction adds an interesting dynamic to deck building and card selection than normally seen in Commander.


Currently 4 CMC shares the same ban list as standard Commander as seen below. Additional bans and possibly unbans may be made after review at a future time.


There are also some odd cases for various cards and mechanics and their legality in the format.


Morph
Morph cards are legal so long as the front side is either a land or spell with casting cost 4 or greater


Modal Double Faced Cards
Modal double faced cards are legal so long as both sides have an individual casting cost of 4 or is a land.


Prototype
The prototype cost for spells with the mechanic must cost 4 or greater


Adventure
Spells with adventure must cost 4 or greater in addition to the adventure spell costing 4 or greater


Split/Fuse/Aftermath
The casting cost of both halves of the spell must be individually greater than 4


More Than Meets the Eye
Cards with More Than Meets the Eye must have both a casting cost and a More Than Meets the Eye cost of 4 or greater


4 CMC ban list:

25 cards with the Card Type “Conspiracy." Click here for list.
9 cards that reference "playing for ante." Click here for list.
Cards whose art, text, name, or combination thereof that are racially or culturally offensive are banned in all formats. This list is a work in progress. Click here for the list.
Biorhythm
Braids, Cabal Minion
Coalition Victory
Emrakul, the Aeons Torn
Gifts Ungiven
Golos, Tireless Pilgrim
Griselbrand
Iona, Shield of Emeria
Karakas
Library of Alexandria
Panoptic Mirror
Paradox Engine
Primeval Titan
Prophet of Kruphix
Sundering Titan
Sway of the Stars
Sylvan Primordial
Tolarian Academy
Upheaval
Yawgmoth's Bargain

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