Start on "Hero".

Regarding Razaz, I've always been surprised. 15 weak, dilapidated golems – how can anyone even play with them?

I wouldn't choose Razaz 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 Razaz, 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 Razaz, the golems are more durable (higher HP, defense, and damage reduction).

Besides, Razaz has an easy path to gaining daily power, which for a mage is almost cheating.