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The damage is small. For a Warrior.
With equal magical power and magical defense of a unit, at level 10 it will deal about 16 damage. On the other hand, playing as a Mage and increasing earth magic and overall magic power can be quite interesting. Also, the damage to each stack, if there are 7 of them (for example, an enemy hero-trickster), will be a total of 110 damage, and 110 free damage each turn is not something you find every day.
Or amber, if you can get it.
In general, it can be useful in certain situations.
However, there is a bug with auras. After the first turn, they stop working.
With equal magical power and magical defense of a unit, at level 10 it will deal about 16 damage. On the other hand, playing as a Mage and increasing earth magic and overall magic power can be quite interesting. Also, the damage to each stack, if there are 7 of them (for example, an enemy hero-trickster), will be a total of 110 damage, and 110 free damage each turn is not something you find every day.
Or amber, if you can get it.
In general, it can be useful in certain situations.
However, there is a bug with auras. After the first turn, they stop working.