I barely managed to defeat him with a Zephyr that dropped in the tavern. It was late, so I postponed it.
Also, the map replaces the hero Maahir with Menelaus.
The starting heroes are also like that; their skills are set by default, but the demon's "junk tactics" won't include fire arrows, the mage's replenishment won't include a super skill, and there's no mentor (possibly not at all). At least he tried to solve these problems.
And moving across the sand is slow.