Undead Don't Have Special EyesightBack to SeanKReynolds.com home
From time to time the argument crops up that undead
can see through all illusions. There are two main ways that people come
to this erroneous conclusion.
Premise #1: Undead are immune to mind-affecting effects.
Conclusion #1: Since all illusions are mind-affecting, including invisibility, undead are immune to all illusions.
Premise #2: Many undead don't have eyes (skeletons have empty sockets, zombie eyes are rotten, incorporeals are just ghostly, etc.).
Since they don't have eyes to receive light, they must be sensing things
in other ways, probably with some kind of life-force sense, and since
illusions don't have life-force, undead see right through them.
Oddly enough, both premises are true, but both conclusions are false. Let's tackle these one at a time.
Premise #1: Undead are immune to mind-affecting effects.
True. It's right there in the description of the standard undead
abilities: "Immunity to all mind-affecting effects (charms,
compulsions, phantasms, patterns, and morale effects)."
Conclusion #1: Since all illusions are mind-affecting, undead are immune to all illusions.
Whoah! Hold it right there. Not all illusions are mind-affecting!
Figments and glamers produce unreal but certainly not mind-affecting
effects. If you use silent image to make an illusion of a cottage, the
cottage may not be physical,
in that it can't shelter you from rain, but it's also not simply a
magical image in your mind. You can disbelieve it, which mean you
recognize it is false image, but it doesn't disappear (notice the spell
says "Will disbelief" not "Will negates."). A lot of people use a
hologram as an analogy for figments (and that's a pretty accurate
comparison if you don't nitpick it too much) ... and clearly holograms
aren't in your mind. Shadow illusions draw upon extradimensional energy
to create things that are semi-real (more than just images or sounds),
so they're not just mental effects either. So the first part of the
conclusion here is false. Since the first part of the conclusion is
false, it can't be used to prove the second part of the conclusion.
So far: One "proof" that undead can see through illusions is shot down.
Premise #2: Many undead don't have eyes.
True, and it's obvious by observation, at least as much as we can't in
the real world: a skeleton doesn't have eyes, and a rotting corpse's
eyes are usually in no shape to be used for vision. While we have no
incorporeal creatures in the real world, it's not much of a leap to say
that creatures that don't have physical bodies don't have physical eyes.
Conclusion #2: Since they
don't have eyes to receive light, they must be sensing things in other
This conclusion is somewhat shaky. Nothing in the descriptions of the
undead presented in the Monster Manual
say anything about them sensing things any differently than living
creatures.* In fact, Sage Advice in Dragon Magazine clarified** that
unless otherwise stated, all creatures have the normal five senses of
humans (sight, hearing, smelling, touch, and taste). None of their
descriptions say they have any unusual sense (unless they have
something like blindsense or blindsight listed). In fact, no creature
in the MM that lacks eyes (like elementals) is listed as having any
special form of sight ... why is it that only undead get this "other
D&D is written for humans. It's written by humans from the perspective of humans, and when comparisons are made, they're made to a baseline human.
Things that aren't outright stated in the D&D should be assumed to
be human-normal. Huge parts of the game are built around the human as
the standard, from armor class (the default AC of 10 is the AC of your
average unarmored human) to attack rolls (your average unarmed human
with no special training has about a 50% chance -- 10+ on a d20 -- of
hitting another average unarmored human with a punch) to saving throws
(default DCs are set according to what your average human could resist,
dodge, or survive) to skill checks (DC 10 is something your average
unskilled guy could succeed at about 50% of the time). With this
humanocentric view, it should be clear that if there is no listed
answer to a question, the answer almost certainly is the same as asking
the question about a human.
How do bugbears poop? Just like a human.
Where do gnomes have body hair? In the same places humans do.
How good is an aboleth's sense of smell? About as good as a human.
How spicy is too spicy to an aasimar? About as much as a human would consider too spicy.
Of course, this comparison doesn't hold up to creatures that obviously
resemble nonhuman real-world creatures. If asked about the sense of
smell or taste preferences of a pegasus, I'd compare it to a horse. If
asked what sort of meat owlbears prefer, fish or chicken, I'd find out
what real bears like. But for undead, the closest comparison is to
humans, since most undead are made from humans (or other humanoids,
which bring the comparison back to humans again).
This is really an aspect of Occam's Razor:
"The simplest of two or more competing theories is
preferable and that an explanation for unknown phenomena should first be attempted in terms of what is already known." - Dictionary.com
So, in this
case, if one explanation is "undead senses default to the human norm
through some process that mimics human senses" and the other is "undead
have some strange method of sensing their environment, even though no part of the rulebooks says that undead have this ability",
clearly the first explanation is the simpler one and is probably
correct. When backed up by Sage Advice's statement that creatures have
normal human senses unless otherwise stated, the evidence is strongly
in favor of the familiar human senses rather than the kooky
One more comment on this point: Of course, all undead do
have a special sense that humans don't have--darkvision. You know this
not only because the undead type entry says they have it, but all
undead in the MM do (or at least should) have darkvision listed. But
the rules also say that darkvision is "black and white only, but is
otherwise like normal sight." "Normal," of course, means "like a
human's" in D&D. And if undead have a special sense, why would they
need darkvision which works like human sight? If they have senses that
aren't like human senses and yet have another sense that is
like human sight, isn't that strange? Again, the simplest answer is that
their senses work like human senses and darkvision is a supplement to
that, just like dwarves have humanlike senses with darkvision as a
probably with some kind of life-force sense,
Here's where things get totally crazy.
First, if undead could sense life force, that would be a HUGE advantage. They could ignore invisibility, mirror image
(which, mind you, is a figment, and as explained above produces a real
image that creatures can actually see, not a mental trick), blindness
effects***, blur, displacement,
magical darkness, most concealment effects, know when a creature is
standing around a corner (unless this "lifesense" requires a line of
effect to the living target), spot hiding creatures automatically ...
and on and on. Clearly the lowly skeleton is a much greater threat
because of this! What evil necromancer or cleric in his right mind
wouldn't keep some skeletons on hand to alert his living minions of
invisibles and such in the area! We must increase the CRs of all undead
immediately! After all, this lifesense operates like a combination of deathwatch, see invisibility, and true seeing!
But wait ... again we run into the problem that none of the D&D
books say that undead ignore invisibility and so on. And this lifesense
brings up a lot of questions. Can they sense nonliving things that
aren't creatures, like walls? Deathwatch says they can recognize nonliving creatures such as constructs but doesn't say anything about recognizing nonliving objects, presumably because the default assumption of a human caster can already sense that a floor exists, but
the lifesense argument cannot use "undead have human senses" as an
assumption because the lifesense conclusion is trying to explain why
undead do not have human senses.**** It would make it a lot harder for undead to get around if their only
perception of their environment was through living or undead landmarks.
Heck, if they can't sense objects, undead monks wouldn't be able to use
Deflect Arrows since they couldn't perceive the arrow in flight or even
as it was leaving the enemy's bow. Same goes for Improved Disarm and
Sunder ... how can you knock a weapon out of someone's hand or attack
the weapon if you can't actually sense
the weapon in the first place? Heck, how can undead pick up weapons and
use them in combat? They can't see a scabbard to attach to a belt
(which they also can't see), and they can't see the sword in the
scabbard. Undead must walk around with their weapons out all the time
because if they ever put down their weapon they'll never be able to
find it again! And good luck using magic items ... a wounded undead
trying to dig a potion of inflict critical wounds
(which it can't see) out of its pouch (which it can't see) so it can
heal itself won't be able to read the label on the potion (since the
label and paper are not living)!
(As an aside, notice the sample vampire in the MM has the Blind-Fight
feat. Why would it ever need this feat if it could sense invisible
creatures and operate in total darkness? You could argue that it had
that feat while it was still alive and just has to "eat" the choice of
a bad feat that does nothing for its undead self (just like the Diehard
feat would do it no good, since as an undead it can never go to
negative hit points). But why would WotC deliberately give a bad feat
selection into a creature in the MM? Wouldn't that make the creature
weaker than its CR would indicate? You don't see them giving Improved Unarmed Strike feat to
longsword-wielding humanoids--which is just as innefectual (and dumb) a choice
as the lifesensing vampire with the useless (to it) Blind-Fight feat. Similarly, the sample elite vampire has Blind-Fight and Improved Disarm, which as I point out about is problematic for the undead that can't sense nonliving things.
So maybe they can sense objects walls and floors and such just as well
as a human can ... but if you're giving them that, why add in on top of
that a special and superior sense that isn't mentioned in the books? If
the whole point of lifesense is that undead don't see things like
humans do, why turn around and say that they do see things like humans do and then slap some goodies on top of that--goodies that aren't mentioned in the core books?
Can you hear with lifesense? Taste? Touch? Smell? No answers. Wait,
undead have to be able to hear, since their creator can give them
verbal commands. So is that a quirk that they can hear only because it
comes from a living creature? Why would this sense differentiate
between sound waves made by a living creature and those that aren't. I
guess lifesense lets you hear. Probably like a human. Which again makes
me wonder why they need a special sense if they're already using human
What about energy? Acid, cold, electricity, fire, and sonic aren't
objects. Can lifesense detect a wall of fire? Can it detect heat at
And what range is this ability? 60 feet? 120 feet? As far as a human
can see? This ability isn't defined anywhere. If it has a limited
range, then the living should have long ago figured out what that range
and exploited it. "An army of undead is on the way? Fear not, just stay
200 feet back and pepper them with arrows, they won't be able to sense
where we are."
And let's talk a bit about animate dead. This is a 3rd-level cleric
spell that not only crams negative energy into a body, but it gives
that undead body this super-powerful lifesense ability! And the
duration is instantaneous,
which means it can't be dispelled. How come some smart spellcaster
hasn't taken that spell apart to find the "give target lifesense" code,
strip out the "cram in negative energy" part, and end up with a
lower-level spell (since it does less than the original) that gives the
target creature instantaneous-duration lifesense? My answer is that
there is no lifesense component, that the default senses of any
creature are human-normal (in fact, I'd let you create a human senses
spell that gave the target human-level senses instead of its own normal
senses, but for most creatures that would be pointless). Some people
might argue, "no, see, the lifesense comes as part of the natural
abilities of the undead life force you're drawing from the Negative
Energy Plane." Ok, I can see that, but that still doesn't mean that
someone couldn't make a spell called summon a little undead spirit to wrap around my head and relay to me what it senses, which would have the same effect as the give me lifesense spell. Yet no such spell exists.
It's easier and simpler to let undead have normal human senses rather
than make assumptions about an undefined yet
omnipresent-in-every-undead lifesense ability that you have to keep redifining and clarifying when it's never mentioned in the books in the first place.
and since illusions don't have life-force, undead see right through them.
If undead have lifesense, and they don't sense things like humans
do, then undead should see right through illusions. But hopefully I've
shot the whole lifesense idea in the head, which means that the first
part of the conclusion is false, and therefore it cannot prove that the
second part is true. (It doesn't mean the second part is false, it just
means that you have no evidence proving it true, and since the burden
of proof is on the one insisting on the truth conclusion, it's up to
you to prove me wrong. Any takers?)
Thus, barring any proof that they do, undead have no inherent ability to see through all illusions
(though they are unaffected by mind-affecting illusions, which is most
And they don't have lifesense, dagnabbit.
* It has been pointed out to me (thanks, Charles G!) that there is one
undead creature with a lifesense ability: the dread wraith. It tells you
exactly what this power does. No other undead is listed with this
ability, not even the regular wraith. So if this is the only undead with this ability mentioned and described, why assume that all undead have it?
** I would have thought they would have put this clarification into the MM 3.5 but it isn't there ... oh, well.
*** Isn't it funny that in 3.5 flare is evocation, blindness/deafness is a necromancy spell, but power word blind
is an enchantment? It's like a Monty Python sketch. "No, really, you're
blind, I insist." "Very well, then." (falls off cartoon cliff)
**** Note that the dread wraith's lifesense ability only mentions
living creatures and the strength of their lifeforce. If you use that
as the basis for your "generic" lifesense ability that all undead (in
theory) have, it still doesn't address whether or not they can see
nonliving things. It's particularly relevant to this rant that the one
creature in the MM that does have a lifesense ability doesn't have any
explanation of how it perceives the rest of the world (answer: the
default answer of "just like humans").