Command Structure is a card type used by all four races:
Command structures must be protected at all costs, because if a player does not have any command structures at the end of a turn, that player loses the game. Other than this constraint, command structures function the same way as any other structure. If a card or rule mentions the word "structure", you should assume it applies to command structures as well.
Each command structure also provides an important role for that race's deck:
- The Nest is the only Rat structure which can produce additional rats
- The Oviary is the only Lizard structure which can produce additional lizards
- The Thinker unlocks forms and upgrades
- The Stagnant Reservoir and Festering Corpse can both spawn Maggots and research upgrades. The Festering Corpse can also reanimate.