There are too many situations where it doesn’t make sense. And I’m going to explain why, but first I’m going to give the good stuff to you right up front. Here’s how I’m handling fear in my games from now on:

If your character is frightened, roll 1d8 or pick what option suits him best from the list below.

Paralyzed with fear, you are rooted to the ground. Fear leads to hatred, and you vow to destroy this abominable thing. Panic! You seek to escape this monstrosity at any cost. Stunned, you gape like an idiot. You cry out in terror. Falling to your knees, you pray to the gods for salvation. The unfathomable awfulness leaves cowering and whimpering. Words fail you. Attempts at speaking come out as stammering nonsense, or they don’t come out at all.

You take a -2 on all rolls against the source of the fear, and you suffer from the effects of the fear for 1 round. I don’t think it really needs more mechanics than that.

That’s the tl;dr version. But now onto the article itself, about why save vs. fear is stupid.

D&D has a history of giving monsters special fear abilities, most of which are ill-considered. For instance, the mummy:

At the mere sight of a mummy, the viewer must succeed on a DC 16 Will save or be paralyzed with fear for 1d4 rounds. Whether or not the save is successful, that creature cannot be affected again by the same mummy’s despair ability for 24 hours. The save DC is Charisma-based.

“The mere sight of a mummy” is so horrifying it can render the commonfolk completely immobile for 6 to 24 seconds. That seems sensible enough. The average person in D&D hasn’t likely seen a mummy before. Only thing is, D&D isn’t about the average person. It’s about grave-robbing adventurers who might very well run into a mummy someday. The first time they encounter a mummy, they are shocked, horrified, and turned into drooling, stammering, wannabe Scooby-Doos. Well, they can’t actually run the other way when they first see the mummy, but the idea stands.

What happens if they flee and come back after that mummy again? No fear, no problem. Unless it’s been a day, in which case they have to roll for fear again, even if they’re loaded down with holy water and flamethrowers, even if the ranger took mummies as his favored enemy. And after they kill that mummy, if they move deeper into the Pharaoh’s tomb, they’ll have to make Will saves against each and every new mummy they encounter. The mightiest of dragons must likewise roll this save. Why? Because this a pile of moldy bandages has that ability.

Dragons have a similar ability known as Frightful Presence:

A young adult or older dragon can unsettle foes with its mere presence. The ability takes effect automatically whenever the dragon attacks, charges, or flies overhead. Creatures within a radius of 30 feet × the dragon’s age category are subject to the effect if they have fewer HD than the dragon. A potentially affected creature that succeeds on a Will save (DC 10 + ½ dragon’s HD + dragon’s Cha modifier) remains immune to that dragon’s frightful presence for 24 hours. On a failure, creatures with 4 or less HD become panicked for 4d6 rounds and those with 5 or more HD become shaken for 4d6 rounds. Dragons ignore the frightful presence of other dragons.

You probably glazed over that wall of text because it’s way too complicated, but the gist is that low-level characters must make a saving throw or flee in terror, while everyone else who is lower level than the dragon must roll to avoid a lesser fear effect. Makes sense, except when you realize that this happens every time the stupid dragon flies overhead. Say good-bye to draconic allies unless they prefer ground-level travel. By the way, a wizard polymorphed into a dragon doesn’t scare people, and neither does a dragon polymorphed into a dragon.

The final reason why save vs. fear is dumb? It only provides one outcome for fear effects. Consider the confusion spell for a bit of guidance: roll a d% to see what your character does. He might fly into a rage and attack the spellcaster, he might babble incoherently, and he might run away. Why? Because it’s a confusion spell, and there are a few things that could go wrong when you’re confused. Fear, though? You’re paralyzed by a mummy, or you take off running from a dragon. Why aren’t there more options?

Hence the options above: roll 1d8 on the list and take a -2 penalty. I don’t think it really needs more mechanics than that.

I should also mention that the innate fear a monster imposes should be a judgment call made by the GM. Yes, you must roll to save vs. fear the first time you encounter the desiccated corpse of the mummy lord, but maybe not the second time you meet him. NPCs shouldn’t get a save at all—they’re either commonfolk, so they panic, or they’re experienced enough that they can deal with the fear.

Alternatively, I might give the creature a fear aura. If you’re in the presence of a Nazgul and your hit points drop below 25, you are terrified and must roll to save vs. fear (if it seems reasonable, mind you).

This is all for passive fear abilities, mind you. Active fear is a different story. When I say “active fear,” I mean things like spells, fear-inducing gaze attacks, mental manipulation, and so forth. To use those, the monster has to make a concerted effort to cause fear, and that should function as normal. A dragon might not be vulnerable to a mummy’s fear, but it might be vulnerable to a necromancer’s fear spell (though probably not too vulnerable).