Does the 'Protection from Evil and Good' spell protect from all listed entities, or just one?

Question

The spell Protection from Evil and Good has the following in its description:

Until the spell ends, one willing creature you touch is protected against certain types of creatures: aberrations, celestials, elementals, fey, fiends, and undead.

In a previous session, a player insisted that the wording "against certain types" meant that when one cast the spell, one selected the type of creature that the protection worked against - and the spell was basically worthless against the other listed creatures during that time.

For instance, if the spell were cast to protect the tank from a Vampire (undead), then the tank would not be protected against the Vampire's demon (fiend) minions.

This seems to be an overly specific interpretation of the spell.

Does the 'Protection from Evil and Good' spell protect from all listed entities, or just one?

Answer 1

The use of the plural form "types" and the word "and" both indicate that the spell protects against the whole list

The spell states (emphasis mine):

Until the spell ends, one willing creature you touch is protected against certain types of creatures: aberrations, celestials, elementals, fey, fiends, and undead. [...]

If the spell were intended to only grant protection against one type of creature it would say something like this:

Until the spell ends, one willing creature you touch is protected against a certain type of creatures: aberrations, celestials, elementals, fey, fiends, or undead.

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This is also supported by the fact that the spell makes no indication that the caster is supposed to choose a type. A phrasing I would very much expect to see if it were intended to only include some of the types listed. Such a phrasing appears in other parts of the rules such as with protection from energy and spirit shroud (emphasis mine):

For the duration, the willing creature you touch has resistance to one damage type of your choice: acid, cold, fire, lightning, or thunder.

[...] This damage is radiant, necrotic, or cold (your choice when you cast the spell). [...]

Answer 2

It protects against all the listed (plural) "certain types".

When a spell wants you to choose one from the list, it will say so. For example, Protection from Energy:

For the duration, the willing creature you touch has resistance to one damage type of your choice: acid, cold, fire, lightning, or thunder.

Answer 3

And means And, not Or

Moreover, 'and' is used twice: One is the very title of the spell, and once as the logical operator over the various listed types.

The spell protects against Good and Evil, because that's what the name of the spell is. The spell protects against aberrations, celestials, elementals, fey, fiends, and undead-- not or, requiring a choice, but and-- all at the same time.

Furthermore, consider the second and final paragraph of the spell description:

The protection grants several benefits. Creatures of those types have disadvantage on attack rolls against the target. The target also can’t be charmed, frightened, or possessed by them. If the target is already charmed, frightened, or possessed by such a creature, the target has advantage on any new saving throw against the relevant effect.

Emphasis mine: Creatures of those types. Not one of those types. Not some of those types. Creatures of those types; all of them. This is unambiguous, because 'types' is pluralized as well as 'creatures.'

That is the only plain English interpretation of that spell. There is no support anywhere for your player's interpretation.

(Going out on a limb: If your player is obsessing over the word 'certain', then the work that 'certain' is doing here is excluding all monster types not on that list, e.g., humanoids, constructs, etc.)

Answer 4

The spell is called "Protection from Evil and Good". Were the suggested reading that only one type of creature should be selected, that means that, for example, choosing "fiends" does not protect from Good. Which would be nonsensical.

Plain English reading: the spell must protect from both, based on the name.

Moreover, nowhere does the spell claim that one type of creature should be chosen.

Plain English reading: one should not be choosing.

It goes on to demonstrate an inclusive list. If a menu describes a pizza as containing peppers, mushrooms, and cheese it has all three, rather than one of them. Thus there is no reason to claim that "aberrations, celestials, elementals, fey, fiends, and undead." is only one of those.

Plain English reading: it has a list of all the things, not a list of options.