You have to beat hard rainbow cup and get gold.
To unlock black mage you have to play with seven characters in the seventh battle chose your best character to unlock him
if you have version 0.7 you can unlock black mage
ACTUALLY you can UNLOCK someone and that is black mage. To unlock him play 10 matches and probably win them
you can unlock 1 is black mage(unlock it by play 10 brawls.)
To Unlock Black Mage-Play 10 Brawls
Complete 10 brawls
You don't black mage is not a character in the game.
On demo 0.7 you can unlock Black Mage by Playing 10 VS Matches.
Black mage is the only character you can unlock by winning 10 brawls
black mage: do 10 matches
yes black mage
Sorry, Unfortunately you can't, the only unlockable character is "black mage". If you are wondering how to unlock him youtube it.