The four zombie ranks also correspond to their relative rarity when opening packs. Minion zombies are the most common contents of card packs, while General zombies are the rarest.
After being played (and immediately before Entry), any zombie with a rank higher than Minion will bestow a special buff based on its Rank and Faction to one or more of your other zombies already on the battleground. The buff can only be given to lower-ranking zombies of the same faction, and is assigned randomly among valid targets:
• Officers buff 1 random minion
• Commanders buff 2 random minions or officers
• Generals buff 3 random minions, officers, or commanders
Note that Officers only grant the ability, while Commanders and Generals grant bonus stats as well.