Do you count as "a creature within X feet" of yourself?

Question

There are various features that affect "targets within X feet".

For example, the Wild Magic Sorcerer's Wild Magic Surge table (PHB, p. 104) has the following result on a d100 roll of 83-84:

Each creature within 30 feet of you takes 1d10 necrotic damage. You regain hit points equal to the sum of the necrotic damage dealt.

Do you take this damage as well and then immediately heal it? (Thanks to user @RallozarX for pointing out that this does matter, say if they are concentrating on a spell)

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Below are some examples I've found arguing that you are a creature within X feet:

There is the sword burst cantrip (SCAG, p. 143):

[...] Each creature within range, other than you, must succeed on a Dexterity saving throw or take 1d6 force damage [...]

Which seems to imply that you do count as "a creature within range".

Then there is the question "Can a character cast Bless on themselves?", and this answer states that "you are always within 30 feet of yourself".

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Below are examples I've found arguing that you are not "a creature within X feet":

The Wild Magic Sorcerer's Wild Magic Surge table result on a d100 roll of 95-96:

You and all creatures within 30 feet of you gain vulnerability to piercing damage for the next minute.

This seems to imply that you would not be considered "a creature within 30 feet".

Then there is the ice knife spell (EEPC, p. 19; XGtE, p. 157), which states:

[...] Hit or miss, the shard then explodes. The target and each creature within 5 feet of it must succeed on a Dexterity saving throw or take 2d6 cold damage [...]

This too seems to imply you do not count as "a creature within 5 feet".

There is also the question "Does the target of Lightning Arrow take the secondary damage too?", and this answer quotes the following unofficial tweet by lead rules designer Jeremy Crawford:

The splash damage of lightning arrow affects each creature within 10 ft. of the target, not the target.

Crawford has also said:

If I say, "Each person within 5 feet of me gets a cupcake," an idiomatic reading of that English doesn't lead to me getting a cupcake.

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Do you count as "a creature within X feet" of yourself?

Answer 1

It's ambiguous, and contextual factors sometimes do and sometimes do not resolve that ambiguity

In the case of Ice Knife the 'target and' phrase does make it clear that 'the target' is not a part of the 'each creature' group later mentioned. That's not because it, strictly speaking, wouldn't be a part of that group but because dealing damage to the target twice, once implicitly, would be weird and therefore is probably not what the sentence is intended to say, particularly sans comma.

In the case of Crawford's tweet, he's completely full of it. 'Each person within 5 feet of me' is not an idiomatic English expression. No one talks like that. If you said that, the overly specific language would mean that people would intuit that the language should be taken in a sort-of legalistic manner and whether they thought that statement included you or not would depend upon the individual listener and particularly upon their familiarity with mathematics. It's actually a pretty good example of a phrasing where a majority of people, at least in California where I live, would definitely interpret that as specifically including you-- in fact such an odd phrasing would ordinarily occur almost exclusively in the context of explaining set theory or categorical syllogisms, where the entire point would be that the statement includes you.

Most statements are somewhere in between these two extremes. Some readers will think that they read one way, while some will think they read the other. Most of the time, those readings will have nothing to do with English language use and instead be based entirely off of the skin they have in the game, as it were. If a reading leads to something being possible that they don't like, particularly if they see it as unbalanced or 'broken', most people will insist the other reading is the only possible one, even when the language is not at all unclear. When the language is actually unclear, such biases are still more powerful.

Depending on the degree to which one can recognize one's biases, then, it may be advantageous to, rather than discussing what the text does say-- which will often leave you with a poorly considered, incomplete, or otherwise deeply flawed rule even should you arrive at a generally true conclusion-- instead discuss what the rule ought to say. You could do worse that to replace an unclear and ambiguous piece of text with something your group thinks makes sense and will work well. In the case of whether these abilities are self-targeting, you'll need to take in on a case-by-case basis, considering how the choices you make impact other features that also affect spell targeting as well as the feature in question, and myriad other factors. Don't expect these rulings to be consistent across groups and remember to ask about ones that are important to your character before play and you should be fine.

Answer 2

A Target In Range is not the same as a Creature In An Area Of Effect

Whether or not you are within X feet of yourself depends on whether you are choosing a target for a spell, or determining if a creature is affected by the area of effect of a spell (or similar).

Target In Range

Targets (PHB 204)

A typical spell requires you to pick one or more targets to be affected by the spell's magic.

Targeting Yourself (PHB 204 -- continuing the above section)

If a spell targets a creature of your choice, you can choose yourself, unless the creature must be hostile or specifically a creature other than you. If you are in the area of effect of a spell you cast, you can target yourself.

This is the source of why "you are always within 30 feet of yourself" when casting Bless.

When a spell lists a range in its description, it is referring to where you can target a spell, and the caster is included in that range.

Creature In An Area Of Effect

Areas of Effect (PHB 204-205)

Spells ... cover an area, allowing them to affect multiple creatures at once. A spell's description typically has one of five different shapes: cone, cube, cylinder, line, or sphere. Every area of effect has a point of origin, a location from which the spell's energy erupts.

Cone/Cube/Line

A cone/cube/line's point of origin is not include in the cone/cube/line's area of effect, unless you decide otherwise.

Cylinder/Sphere

A cylinder/sphere's point of origin is included in the cylinder/sphere's area of effect.

So, sometimes the area of effect includes the creature at the point of origin, sometimes it doesn't. In many (but not all) cases, the caster gets to decide.

DM adjudicates ambiguous cases

Sometimes a spell doesn't say the shape, it just says "within X feet".

In those cases, it appears to be consistent that, unless it says otherwise, the target is not included.

However, just a vague "within X feet" would imply to me to indicate a sphere, which means a target is included.

I could find no explicit rules on which to follow, so ultimately it is up to the DM to decide, based on what makes sense for their table.

I personally follow the convention of not including the target of an effect when the words "within X feet" are used without a shape, as it generally results in the least absurd or ridiculous result (like having a Wild Magic Sorcerer immediately be healed for the damage they just took.)

Specific Situations

Sword Burst

Sword burst has a range of 5 feet, and the description states that all the creatures in range are targeted. Normally, this would include the caster, which is why it explicitly states the caster is not included in the description. Note that this is NOT an area of effect, so those rules don't apply. This just falls under the normal Targets rules.

Bless

Bless has a range of 30 feet. Under the Targets rules you are included in that range, so you can target yourself.

Ice Knife

Ice Knife has a range of 60 feet, and a spherical area of effect of 5 feet. As the target is at the point of origin, and a sphere's point of origin is included in the area effect, the description is simply restating the normal rules for who is included in the damage. The OP says this implies that the target is not normally included, but I think this wording was used simply to help make it clear that the target is affected as well, for those that don't have the area of effect rules memorized.

Lightning Arrow

For this spell, the range is self -- meaning the caster gets to enhance their ranged attacks, not that they are attacking themselves.

There is no area of effect for this spell, but rather the damage description is customized... and vague. This is where I wish the rules provided explicit guidance on when then is an area of effect that doesn't specify a shape.

The Wild Magic Surge examples in the OP also fall into this category of vagueness, but in each of these cases I would rule that the caster/target is not included in the resulting effect.