Common cards are now capped at 4 instead of 3.
In other words, “not more than 4 of any individual common” can now be played in a Primordial deck. This change is the result of a poll and community discussions that took place on the Primordial Discord server. In short, the x4 seems more popular than the x3 and it will help to restore the balance between aggro and control. On the other hand, the rarity restriction will be kept (which benefits control more than aggro).