Does a creature have to see to be affected by the Fear spell initially since it is an illusion?

Question

Does a creature in the target area of the Fear spell have to be able to see to be affected by the spell when cast, since it is an illusion? It is not worded like Hypnotic Pattern which explicitly says so.

Also, what determines if there is nowhere to move? If they can move 5 feet, do they take the Dash action and stop? Would they have to move their full movement before taking the Dash action? How much space is needed? What if the way isn't safe (for instance, running into the druid's Spike Growth is the only way away from the Fear caster)? None of this is obvious to me from the spell.

Answer 1

No, they can be affected even if they can not see.

The description of the spell does not require that the target(s) have to be able to see for being affected:

You project a phantasmal image of a creature's worst fears. Each creature in a 30-foot cone must succeed on a Wisdom saving throw or drop whatever it is holding and become frightened for the duration.

---

Answers to the other questions:

1. Also, what determines if there is nowhere to move? If they can move 5 feet, do they take the Dash action and stop? Would they have to move their full movement before taking the the Dash action? How much space is needed?

The spell's text says (emphases mine):

While frightened by this spell, a creature must take the Dash action and move away from you by the safest available route on each of its turns, unless there is nowhere to move.

If there are just 5 feet, the target must take the dash Action and move 5 feet. In case there is nowhere to move, the creature can take other action, but under the Frigthened condition:

• A frightened creature has disadvantage on ability checks and attack rolls while the source of its fear is within line of sight.
• The creature can't willingly move closer to the source of its fear.

2. What if the way isn't safe (running into the druid's Spike Growth is the only way away from the Fear caster?

This question should require a little bit more of context, but the spell description provides again how to rule in this case (emphases mine):

While frightened by this spell, a creature must take the Dash action and move away\$^{(1)}\$ from you by the safest available route\$^{(2)}\$ on each of its turns, unless there is nowhere to move\$^{(3)}\$.

If the sole way to run away from the caster is passing through the druid's Spike Growth, then the target(s) will do it. Indeed:

• Is there any possible route? Yes, the space affected by the druid's spell (3).
• Is it the safest? Yes, because it is the only one (2).
• Do the target(s) have to move? Yes, because they must take the Dash action and move away from the caster (1).

For more complex cases, see What constitutes a 'safe route' for the Fear spell?

Answer 2

No, it does not need to be able to see for the initial effect

There is a principle that spells do what they say they do. If the spell does not say the target has to see the source to be affected, then it does not. Fear says:

You project a phantasmal image of a creature's worst fears. Each creature in a 30-foot cone must succeed on a Wisdom saving throw or drop whatever it is holding and become frightened for the duration.

There is no language there about needing to see the caster.

In addition, a phantasm is traditionally an illusion that is created in the mind of the creature, not externally. For example, phantasmal forces says "You craft an illusion that takes root in the mind of a creature". That would also support why they do not need to actually see anything to be affected.

For the other questions:

If they can move 5 feet, do they take the Dash action and stop?

While frightened by this spell, a creature must take the Dash action and move away from you by the safest available route on each of its turns, unless there is nowhere to move.

If they can move, they always must take the Dash action, there is no exception. They will move as far as the movement from the Dash action and their other movement allows.

Would they have to move their full movement before taking the the Dash action?

The order in the text is that they first take the Dash action, then move, but I do not think it matters.

How much space is needed?

From the wording it is not entirely clear if the "... unless there is nowhere to move" extends all the way back to the Dash action, or only refers to the movement part of what comes before it. I think that it makes more sense for it to apply only to the movement: it would be narratively weird if they would need to take the Dash action to move 5 feet and therefore could not take other actions¹, but they do not need to take the Dash action if there is nowhere to move, and instead can use their action to attack you. But I think this will be up to the DMs interpretation/adjudication.

What if the way isn't safe?

The text does not say they only need to move if there is a safe route. They have to use the "safest available route", that means if all routes are dangerous, then they need to move through harmful territory, as long as they can move there. If the only route leads through a Spike Growth area, that is an available route and also the safest available route, and they will need to take it. They can pick the least harmful, e.g. if they have the choice between a lava stream and a thorn bush, they can take the thorn bush, even if it means a less direct route of getting away.

---

¹ Well, at least not without bonus action tricks

Answer 3

No, blind creatures are affected.

The image isn't projected into space, it's projected into the mind of the target.

---

If you check the Pathfinder 1e rules, you'll find nomenclature to describe different types of illusions based on how they affect a creature. 5e is often similar (having D&D 3.5 as a common ancestor), and many of these are based on standard English meanings.

• Figment

  A figment spell creates a false sensation. Those who perceive the figment perceive the same thing, not their own slightly different versions of the figment. It is not a personalized mental impression.

  Because figments and glamers are unreal, they cannot produce real effects the way that other types of illusions can. Figments and glamers cannot cause damage to objects or creatures, support weight, provide nutrition, or provide protection from the elements. Consequently, these spells are useful for confounding foes, but useless for attacking them directly.

• Glamer

  A glamer spell changes a subject’s sensory qualities, making it look, feel, taste, smell, or sound like something else, or even seem to disappear.

• Pattern

  Like a figment, a pattern spell creates an image that others can see, but a pattern also affects the minds of those who see it or are caught in it.

• Phantasm

  A phantasm spell creates a mental image that usually only the caster and the subject (or subjects) of the spell can perceive. This impression is totally in the minds of the subjects. It is a personalized mental impression, all in their heads and not a fake picture or something that they actually see. Third parties viewing or studying the scene don’t notice the phantasm. All phantasms are mind-affecting spells.

• Shadow

  A shadow spell creates something that is partially real from extradimensional energy. Such illusions can have real effects. Damage dealt by a shadow illusion is real.

The linked page is from a different system, so the details are going to be different, and DnD 5e might have different definitions for these terms. But it clearly illustrates that the old adage "seeing is believing" is not universally true. We can't assume all illusions are visual, and we can't assume that blind creatures are immune to illusions. We need to read the description of the spell to find out.

You project a phantasmal image of a creature's worst fears. Each creature in a 30-foot cone must succeed on a Wisdom saving throw or drop whatever it is holding and become frightened for the duration.

Fear does not indicate that the creature must be able to see to be affected, so even blind people are affected by it.

Supporting this is that Fear is described as creating a phantasm, and these have historically been purely mental effects. The standard English meaning of the word "phantasm" (2. "a figment of the imagination"; 1.c. "a product of fantasy: such as a mental representation of a real object") also implies it being in someone's mind, not visible with eyes.

From that, we can gather that the image isn't projected into space like a hologram, but rather into the minds of the targets instead.

---

The subquestions have already been suitably answered by Eddymage.