I wouldn't recommend taking Razzak against the AI. He's much more interesting against a human opponent.

Defense for mages is difficult to acquire, but essential against most factions, and it's available from the start here.
With Razzak, the Golemageddon tactic (yellow golems + Armageddon) is interesting. As a last resort - Fireball. This allows you to deploy only golems against the opponent's army and cast Armageddon: we heal, the opponent dies.
Under Razzak, the golems are more durable (higher HP, defense, and damage reduction).

Besides, Razzak has an easy way to gain bonus daily power, which is almost cheating for a mage.