What makes Order Empire special?
Order Empire, unlike Chaos and Elemental Empires, is unique for its Merics, allowing front line troops to heal before, during and after a battle. Unlike the other Empires, Order troops can be cured of poison, which saves a lot of Gold and Mana in case some of your troops die due to the poison. Order is also the easiest to master, making it the most popular Empire among players.
Disadvantages
Like Chaos and Elemental, Order has powerful troops and unique traits that separate it from the others. Unlike the other two, however, it has the weakest and strongest ranged units. The Archidons are cheap and train quickly, however they only have 1 bar of health, meaning they're done for if they get targeted first, get poisoned or burnt, or their Merics are busy healing other units.
Allbowtross are unique units, being able to deal a shit ton of damage and withstand most attacks without losing half their health. But they're slow, making them easily killed when retreating.
Order's powerful Magikill and vital Merics are also very slow, so they either retreat first or die in the process.
Unique Units
Both the Meric and Shadowrath are very unique as compared to the other characters. The Meric is the only unit that can heal and cure, and the Shadowrath is the only unit that can cloak, assassinate and turn the tide of battles really quickly. The Shadowrath can also be used to scout, and if the enemy tries to kill him, get him back before the enemies have a chance to chase him down.
The Spearton is easily the most recognizable warrior, making Speartons an all-time favorite by experienced and new players alike. The Speartons' unique ability to block and bash prevents enemies from attacking more powerful units behind them, and the very fact that they can block up to 40% of incoming damage proves that they can take a lot of hits before going down, unlike other units that take the full amount of damage. They're powerful and flexible, and can be used as foot soldiers or tanks.