Just got this game from Steam sale and i reach lvl 15 as a mage.
Test out the firewall just now. Its really good but you're require to get into melee range and get beat to a pulp by other melee mobs. Quite fun.
If a tank able to use firewall, their damage should be extremely low unless they invest in a lot into Int to make thing a bit more balance for the mobs. O wait nvm tehe