Heh... but what about playing as the Academics? When a Chaos Mage has only five (five, right?) spells that cannot be reflected by a Magic Mirror? And they also have a counterspell. Academics have three times more mana than a Warlock; you can consider your first spell to be your last in that battle.
Also, the Academics' skills mostly focus on strength and knowledge. And their troops are slow and not very proactive.
You can destroy half of the mages' army with a warrior hero on the very first turn.
You can also try this strategy with the Undead; their troops are also not very well-protected and are fast.
You can also try it with Demons; you need to attack them at the beginning so that fewer troops are summoned.
And a hero with only one magic skill is not yet a mage, and not even a combat mage; it's a warrior with magic... you can, for example, take Light or Darkness as support for combat skills. Although 2%...
In my opinion, a combat mage is a balance between magic and an army.

As for small maps, you can also easily choose combat skills on them; at least, I can always do it when I want to.
The Warlock's primary combat skills are developed... well, attack is usually very high (my observation). And defense... by visiting Marletto's Tower, it reaches 1 by the final battle.
By the way, I noticed that if you develop a hero as a warrior, then the skills also tend to focus more on attack and defense. No, on attack... and a little bit on defense.