Does Voice of the Chain Master allow casting certain spells from an isolated space?

Question

An interesting question popped into my brain recently while researching the Pact of the Chain for a Genie Patron Warlock. Casual shenanigans aside, I was wondering if taking Voice of the Chain Master allowed me to cast certain spells while safely tucked in my vessel but, maybe not in the way you think I'm going to ask about. Allow me to elaborate;

As per Voice Of The Chain Master

You can communicate telepathically with your familiar and perceive through your familiar's senses as long as you are on the same plane of existence. Additionally, while perceiving through your familiar's senses, you can also speak through your familiar in your own voice, even if your familiar is normally incapable of speech.

I'm led to believe that Bottled Respite is NOT another plane of existence, since similar items like a Portable Hole specifically mention when they are.

You can use an action to unfold a portable hole and place it on or against a solid surface, whereupon the portable hole creates an extradimensional hole 10 feet deep. The cylindrical space within the hole exists on a different plane, so it can't be used to create open passages.

I think it's safe to assume then, that the interior of the Vessel is simply 'bigger on the inside' and not an isolated dimension that you're teleported to. With this in mind, let's clarify one more subject before moving on.

I want to be clear; I'm not using my Familiar to 'carry' the spell. I understand those limitations. I'm using them purely for approximating my own visual range and my interest is in the wording of certain spells that require you to target 'a creature you can see within range,'which also don't otherwise state the spell 'traveling' through space in any specific fashion. Let's set up our hypothetical from here, and pick a spell I personally think would have suitable water retention for this argument.

My Warlock is safely within a collar or ring (The Vessel) worn by my familiar (standing or sitting against nearest wall in the forward facing direction of the ring, to avoid losing as much spell range as possible), through which, I am perceiving through their sight as though I'm in their space (technically, I am, since they are carrying me.) I want to cast Flesh to Stone and I see a creature within 60ft of me (and am confident the range is correct because me and my familiar are occupying the same space). I cast Flesh to Stone which has a range of 60ft and, has the following description;

You attempt to turn one creature that you can see within range into stone. If the target's body is made of flesh, the creature must make a Constitution saving throw. On a failed save, it is restrained as its flesh begins to harden. On a successful save, the creature isn't affected.

A creature restrained by this spell must make another Constitution saving throw at the end of each of its turns. If it successfully saves against this spell three times, the spell ends. If it fails its saves three times, it is turned to stone and subjected to the petrified condition for the duration. The successes and failures don't need to be consecutive; keep track of both until the target collects three of a kind.

If the creature is physically broken while petrified, it suffers from similar deformities if it reverts to its original state.

If you maintain your concentration on this spell for the entire possible duration, the creature is turned to stone until the effect is removed.

RAW it seems pretty sound from my point of view but, I also just really like this combat tactic so, I may be overlooking something. Thoughts?

Answer 1

The vessel is a separate plane of existence so you cannot see through your familiar's eyes

The Bottles Respite feature states:

[...] The interior of the vessel is an extradimensional space [...]

The following question establishes that extradimensional spaces are separate planes of existence, and thus, entering the vessel prevents you from seeing through your familiar's eyes:

• Does the Mordenkainen's Magnificent Mansion spell's mansion exist on a separate plane of existence?

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Even if you could, spells still require a clear path to their target

The rules on "Targets" states:

[...] To target something, you must have a clear path to it, so it can't be behind total cover. [...]

Meanwhile, the flesh to stone spell has you choosing a creature to be affected (it has you targeting a creature) and as such you are required to have a clear path to that creature, which you cannot have from within the vessel.

Now, if there is a spell that requires you to see something, but does not require you to target that something, then yes, you could use it while seeing through your familiar's eyes. I cannot think of particularly many spells that function like this, though one such example would be misty step which does not require a clear path to its destination because it has a range of self.

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A small note, as @MivaScott pointed out in the comments: the find familiar spell states (emphasis mine):

[...] Additionally, as an action, you can see through your familiar's eyes and hear what it hears until the start of your next turn, gaining the benefits of any special senses that the familiar has. [...]

Beginning to see through your familiar's senses requires you to spend an action, so you could not start to look through them and cast an action spell on the same turn (in most cases... there are exceptions such as through the Quickened Spell Metamagic and Action Surge features).