Olog-hai are resistant and you can feel their presence on a battlefield.
Sappers often made an entire assault bugged (attackers stopped near walls) and cavalry is rather weak. Which are the best - In my opinion, Olog-hai are the best choice. Olog-hai - an assault army is supported by Olog-hai that can destroy fortress' walls. Mounted Cavalry - an assault army is supported by orcs riding on Caragors. Sappers - an assault army is supported by suicide sappers that charge at a fortress' gates. Before you attack an enemy fortress, you can select upgrades that will make siege easier.
