The concept is very simple, but it works, and feels like a far more practical implementation than lets say, a battle card
Because these cards are so rare, it doesnt matter that they arent perfect
By paying two generic mana and one blue, you can have it enter the battlefield with just the Mirror Room door unlocked , and so, when it enters, you can make a Reflection token copy of any target creature you control
For one black mana and a few sacrificed Squirrels, you can give any creature +X/-X, either pumping up one of your creatures a bit or taking down your opponents commander at the cost of a few creatures.
This built-in protection makes commanders like Toph, the First Metalbender a persistent threat