Can "Friends" be used to make any creature in the universe hostile?

Question

Friends is a cantrip with a range of self that reads (PHB, p. 244):

For the duration, you have advantage on all Charisma checks directed at one creature of your choice that isn’t hostile toward you. When the spell ends, the creature realizes that you used magic to influence its mood and becomes hostile toward you.

Since the range is "Self" and the spell does not specify restrictions apart from being non-hostile do usual targeting restrictions apply? If not then could a PC with this cantrip make any creature, on any plane of existence, hostile? This seems rather powerful although not easily useful.

Answer 1

Yes you can affect any creature.

tl;dr You can affect any creature, but the spell does not make the other creature aware of the caster nor can it be expected to have much of an impact on a creature the caster doesn't interact with.

Similarity to dream in wording and affecting other distant creatures.

The friends cantrip is worded similarly to dream in that they target self and affect another distant creature. Friends does not have the restrictions dream does. Using dream on a distant creature is a more familiar use, but it is another example of this sort of effect.

The nature and level of hostility.

A few definitions of hostility[1,2] could apply here to the story:

opposed in feeling, action, or character; antagonistic

marked by malevolence : having or showing unfriendly feelings

Both of those make perfect sense for a creature that is aware of the caster's existence. One that was otherwise of a positive disposition towards the caster would not be after the spell ends.

Ineffectual when the creature is unaware of the caster's existence.

The result of the spell in the reaction of the creature depends on the nature of the interaction the caster has with it.

Another creature might seek retribution in other ways (at the DM’s discretion), depending on the nature of your interaction with it.

A creature that is utterly unaware of the casters existence and has never had any interaction with the caster would essentially be unaffected in that there would be no reaction from them. A creature with zero interactions with the caster would be expected to take zero actions as retribution.

Predisposed to enmity

A functional effect of using the spell to affect a creature that doesn't know the caster is that the hostility may linger even if they're unaware of it such that they do not like the caster when they meet them for the first time.

Answer 2

Technically, you can use friends on anyone from anywhere

The friends spell has a range of Self and states:

For the duration, you have advantage on all Charisma checks directed at one creature of your choice that isn't hostile toward you. [...]

The description puts no limit or restriction on the "one creature of your choice" besides that that must not be hostile toward you, they can be at any range, on any plane of existence whatsoever.

A possible counterargument would be that the affected creature is a target and so you need a clear path to them

However, what counts as a target for a spell is greatly debated and not well agreed upon. So say friends does require a clear path to the affected creature. I would then bring up the scrying spell which also has a range of Self is discussed in the question "Does the Scrying spell require you to have a clear path to the target in order to work?." If friends requires a clear path then scrying likely would as well which is... problematic at the very least. Thus, we assume friends can target anybody, anywhere.

What happens when friends ends? Technically, the affected creature becomes hostile

Quoting again the spell (emphasis mine):

[...] When the spell ends, the creature realizes that you used magic to influence its mood and becomes hostile toward you. [...]

Technically, the spell ending forces the creature to become hostile toward you, this is because there's not a causal link between the creature realizing you influenced its mood and it becoming hostile toward you. The former is a not a requirement for the latter to occur, reading the text literally. I believe this is a rather absurd interpretation and it is not what I, as a GM, would follow.

How I would run this at my tables

I would rule that if you use this spell on somebody and never even direct a Charisma check at them, then you have not influenced their mood and so they have no reason to become hostile toward you. I would rule this on the basis of realism and to avoid making this spell just absurd.

Keep in mind the amount of leeway the GM has with friends

The spell states:

[...] A creature prone to violence might attack you. Another creature might seek retribution in other ways (at the DM's discretion), depending on the nature of your interaction with it.

You haven't even interacted with the creature in any meaningful way, you cast a spell that affected them but they don't know who you are, nor have you directed any Charisma checks at them. Furthermore, it is entirely up to the GM how a creature responds to and uses this newfound hostility, assuming they do anything at all.

Answer 3

Not unless you make a Charisma Check against them.

If I cast Friends on myself, targeting the barkeep, but end up in a 2 minute argument with the barbarian and never manage to actually use the spell to try and convince the barkeep to give us a free round she'll be none the wiser. She may notice I've cast a spell, but as long as I don't actually make a Charisma check against her then I haven't "...used magic to influence its mood..." and she doesn't become hostile.

Answer 4

Yes, but creatures are not thereafter forced to remain hostile

The friends spell can affect any non-hostile creature the caster can 'choose'. When the spell ends, regardless of why it ends, the affected creatures realize, even if it is not true, that you have influenced their mood with magic and, separately, become hostile. Some other spells, like Mind Blank, may render creatures immune to friends, but barring such an effect, this works.

Hostility, and other reaction attitude things, is not an autonomously immutable property of creatures in 5e, though GMs often run it that way. Nothing prevents creatures from changing how they feel about other creatures at any time and for any reason or none at all. How NPCs react to you casting friends on them is up to the GM, but at least some characters shouldn't let the magically conferred hostility dictate their future actions or state of mind.

Note also that this is how the spell works according to its text. Most 5e games that I have seen do not generate conclusions about what abilities can do from the rules text-- they have preexisting ideas about what sorts of things are "reasonable" and then backport those ideas onto the text even if it is directly contradictory. In other words, using this spell to the full extent textually possible is unlikely to work in a real game unless you yourself are GMing.