I would build a tavern on the first turn: this accomplishes two things at once – we harass his hero (we need to find out if he bought Ingmar or a dwarf) and buy either Dugal or someone else – the main thing is to get more melee units. And with Vittorio, we immediately start rushing. He will definitely get a ballista after the first development, which is exactly what we need. The dwarves have nothing to counter it at the start...

The only downside to this tactic is that it only works on maps where the players are not separated from each other by high-level mobs.