Which Orc hero do you prefer?

You can also level up Garun against the Haven faction. Their attack stacks are not very strong, and they usually rush forward. Dryads, Dancers. And even Archers aren't that tough... You can quickly gain attack power.

The Haven faction usually has extremely high defense and a skill, so a Battle Defender will definitely be effective against Garun. But yes, you can already level up quite well with just Dryads, blue archers, and dancers.