A stack with 25 soldiers will be safe from most attacks, but very dangerous monsters exist that can challenge even a very powerful stack. Missile weapons are also valuable against monsters, as few monsters have the intelligence to take advantage of missile combat. Dumb monsters will attack any stack they outnumber. Smarter monsters will evaluate the combat strength of a stack before attacking. Fortunately such monsters are rare.
All monsters fight to the death when they attack or are attacked.
Many monsters will kill and eat any prisoners they take, although they may release prisoners if already well-fed. A few, like bandits, will merely strip prisoners of all their valuables and turn them loose again. Some monsters will rush to join in when they see other monsters attack. For instance, wolves run in packs and will usually aid other wolves. Bandits are quick to take advantage of any combat, and may join in a battle if they see an opportunity.