If there is anything that puts me off about modern fantasy role playing games, it’s the obsession with making monsters defined exclusively by how they deal with adventurers. You never encounter a strange bear. You encounter a bear with anti-platemail can opener attachments and the ability to cast spells invented by humans. Why isn’t it just a bear?

What this really means is that games often are limited by their combat system, and both unwilling and unable to have traits outside of combat with people. You end up with horses with no hit points and tigers with tentacles.

Speaking of, the displacer beast is the most significant example of this. A large cat has tentacles specifically to prey on knights. No, tentacle cat it is not a repository for your source code with a funny mascot. It’s something people seriously use to define their franchise. Dragons, chimeras, and hydras were not interesting enough. They needed tentacle cats.

Moving past this example, displacing it if you will, it gets even weirder. You will never encounter a humanoid monster that is good at killing its own kind. They are always made of fire, immune to fire, and only able to make fire. This means their society is either overrun with criminals that they can’t deal with, or they fight the most frustrating wars, and have yet to win one.

Societies create weapons to deal with themselves. That’s what weapons are. If you are not meaning the weapon to kill your own kind, it’s a tool or it’s for hunting. Swords are invented to kill, but somehow the entire extra-planer’s idea of pest control is swords. When is the last time you hunted with a sword, or caught a mouse with a battle axe? Weapons should be weapons. Societies should have concepts of violence and ways to control violence.

In the Monster Guide for Akkadian Rhythms this is explained very clearly. If you are creating a new monster with a society, the guidance for the soldiers archetype is as follows.

“Create a soldier as a henchman or enforcer, model it as someone who is specialized in fighting their own kind in wars.”

The soldiers should explicitly be designed to fight other soldiers of their own kind. This brings the society to a tangible reality. It also makes combat way more dynamic. Don’t make them target adventurers. Make them have to use their resources in a clever way to engage in a different threat.

Edit

I don’t normally do this, but there is one more thing to add. Monster traits in all editions of D&D are built around foiling oddly specific player advantages. I’m not even talking about magic resistance or immunity to normal weapons. We’re talking about every monster after picking up a vorpal sword has 10 heads or is an amorphous blob. They are designed this way to foil vorpal swords. You get the most uninteresting ideas when all traits are built towards foiling player advantage.

Players enjoy dynamic fights. A monster doesn’t have to be magically impervious to any creature possessing exactly 2 arms due to dealing with 2 armed space pirates for centuries just to create a challenge. There can be one that just has a lot of abilities that shapes the battle field and heals while standing on dirt. Combine that with some soldiers up front and you have a dynamic fight. All without the pulp dinosaur space fiction sprinkled in to diffuse a magic item you don’t like.