
Azothath |
Comport Message (Cmprt Mssg){the abbreviation}
Source: Azothath's Homebrew
School: divination(D); Domain/Mystery: artifice 2; Level: witch 2, wizard 2, cleric 2, inquisitor 2, shaman 2, warpriest 2, medium 2, occultist 2, psychic 2, spiritualist 2, alchemist 2, investigator 2.
Casting Time: 3 rounds
Components: S, M (prepared vial(4 fl-oz container) to wine bottle(24 fl-oz) and 2 pages of parchment or vellum 25gp)
Range: Touch
Target(s): prepared material components (objects)
Duration: up to 2*CstrLvl days
Saving Throw: none; SR: no
Description
The caster prepares the components and seals one blank page in the bottle. The companion page(second page) is usually stowed in the caster's spellbook or scroll case. The bottle is usually given or sent to the recipient. It is a perception DC 0 to notice that there is writing on the page in a sealed transparent bottle. Destroying the companion page destroys the bottled page in a similar manner. Once the bottle is opened the connection to the companion page is broken and the companion fades and crumbles. When the duration ends the pages wither to a near useless brittle yellowed state and crumble if handled. The caster can only have his Int Bonus in active comport message spells at any one time otherwise the oldest two expire with the casting of a new spell.
Within the duration, the companion page can be written upon using conventional methods within a single 2 minute session and the writing appears on both pages if they are on the same plane of existence. Up to 45 words, 200 characters, or a rough map can be conveyed within the 2 minute session. Needless to say the writing session is comprised of full round actions in an undisturbed out-of-combat state. In combat the caster must make concentration checks DC 13 every round otherwise the writing session ends.
Targeting the bottle with an erase spell ends the comport message spell.
Including a fine eye agate of 25gp with the preparer's arcane mark or sigil in the bottle can act as a focus for the casters divinations within the comport message duration.

Azothath |
see also (spell, magic item, weapon, special material, feat, monster, purchased mount, etc) along with several builds in the Advice forum (wizards & archetypes, wizard multiclass, bards, clerics)...
Azothath's Homebrew - spell: Discorporation:C0
Azothath's Homebrew - spell: Abate Affliction:A1 or C1
Azothath's Homebrew - spell: Celestial Healing:C1{rework}
Azothath's Homebrew - spell: Twilight Knife:K2{rework}
Azothath's Homebrew - spell: Lsr Shadow Walk:I4

Pizza Lord |
If I am reading this correctly:
The caster prepares the components and seals one blank page in the bottle. The companion page(second page) is usually stowed in the caster's spellbook or scroll case.
1. The spell is cast upon a pair of parchment or vellum sheets and upon a bottle. One sheet is placed in the bottle and the other (companion) is not. The parchment put into the bottle must be blank.
Within the duration, the companion page can be written upon using conventional methods within a single 2 minute session and the writing appears on both pages if they are on the same plane of existence.
2. If the companion page is written (or drawn) upon, similar writing appears on the bottled paper, which is probably rolled inside the bottle. But this only happens once, and once writing begins there's only 2 minutes, after that, the duration remains, but no more writing is conveyed between the paper. Anyone can write on the companion paper, not just the caster.
It is a perception DC 0 to notice that there is writing on the page in a sealed transparent bottle.
3. The message can be read through a clear bottle at DC 0, presumably at some other DC for a colored or otherwise murky bottle. Presumably there's distance penalties? So DC 1 to notice writing from 10 feet away, and DC 10 from 100 feet? Seems pretty easy for a piece of paper potentially in a 4 oz. vial (about the size of your pinky). I guess there could be some size modifiers (+16 for Fine at best maybe). Granted, you didn't say 'read the paper' at DC 0, but adding in all that ambiguity (or trying to cover all the bases) just clutters up all the writing and space.
Destroying the companion page destroys the bottled page in a similar manner. Once the bottle is opened the connection to the companion page is broken and the companion fades and crumbles.
4. If the bottle is opened, the companion page fades and crumbles. If the companion page is destroyed (presumably if it fades and crumbles from someone opening the bottle to retrieve the bottled paper), the bottle paper is similarly destroyed.
------------------------------------------------Assuming the above is correct:
The issues I have are how unwieldy or unintuitive it is and some of the wording can be tightened up.
1. Do you really need a bottle? Is there any reason you can't just link the two sheets of parchment? It's up to the primary parchment holder to keep it safe, in a bottle or scroll tube or not. It would save you a good amount of space in the components line and you don't need to worry about Perception DCs for trying to read it through a clear bottle, or a dirty or murky bottle, or colored glass, or if they didn't realize that and just used an opaque bottle. It would also save you from worrying about whether the writing on the companion page could really be seen or read on the scroll in the bottle, since it would logically be rolled up at the very least (and what if the companion page user accidently wrote on the side that would facing the interior of the bottle accidently, I mean, they were both blank when put in, it's a reasonable thing that could happen!)
You can avoid all of that by removing the need for the bottle (I guess you could just have the words appear on the bottle and not worry about scroll position or orientation inside it, but whatever).
2. Material components: The vial/bottle takes up space. I know I mentioned it above, but you give sizes from 4 oz. to 24 oz. A 4 oz. is like a 5-Hour Energy bottle, I am not sure what kind of parchment or scroll could be put into that?
Why 25 gp (12.5 gp ea.) for a pair of parchment or vellum? Parchment (suitable for making magic scrolls is 2 sp, Paper is 4 sp.) I don't see the reason except to make it not eschewable (which makes sense, but if it was, there'd be nothing to write upon anyway. I think you could get away with making them '1 gp' or '1 gp ea.' and still be fine without some other reason for the cost.
3. The addition of the fine (fire?) eye agate (25 gp) with the caster's mark being placed into the bottle to function as a focus for the caster's divinations. It doesn't seem necessary. What divinations are you foreseeing that the caster of the spell would cast to locate the gem (or the bottle it's in)? Very few work on items. Locate object would (it within the range), but a caster can already visualize the specific bottle. I am sure there's some spell that might work, but it just seems too ambiguous for what it requires (a specific gemstone of a specific type, for a murky reason).
-------------------------------------------------
If I were to try and edit it a bit, accounting for changes above (which doesn't mean you have to, but maybe the wording will help you consolidate your version):
'Components: S,M (Two blank, specially-prepared parchment or vellum sheets, 1gp ea.)
Targets: The material components
Duration: 2 days/caster level
Description
The caster chooses a primary and secondary sheet. Once during the duration, for up to two minutes, anyone writing upon the secondary sheet creates identical markings on the primary as long as it's on the same plane. Typically this can be up to 45 words, 200 characters, or a rough sketch (or actually time the player doing it). If interrupted, no more markings will be shared, even if the full two minutes were not used.
An erase spell targeting either parchment ends the spell. If the companion page is destroyed, the primary is also destroyed and both pages age, yellow, and crumble to dust when the duration expires. A caster can have a number of active comport message spells equal to their casting ability modifier (minimum 1). Casting a new spell above this limit ends the oldest two.'
Or something like that.

Azothath |
...
thanks. I know my rulez jargon can seem like a bear trap (as it is) and opaque at times as I'm not explaining everything or triviata. I use an intro paragraph and then 1-2 paragraphs of mechanics in a procedural use flow followed by a paragraph of exceptions, interactions, and details. I know it may seem odd and stiff to the creative crowd. This ain't Lord Dunsany.
The materials cost include various reagents etc. Writers don't mention those except in the description, wasted details really. As written my 25gp of materials could be a vial, flask, bottle, jug, large test tube, paperweight, etc. That's intentional. If your dumb enough to put your message in a clay pot - so be it. I used the word "prepared" to denote that something's going on.I did think about erasing the companion page. If you notice it will likely lack line of effect to another caster and is probably blank. What's to erase? So it is going to be situational and left to the GM to adjudicate so I only need detail the bottle and lead the GM to a decision.
As this is a prepared limited duration magic item you need to define available uses at any one time to keep a lid on abuses.
I'll add I know a few GMs that would want an NPC/player to make a perception check to notice a message in a bottle. That line is there to enforce ease of use/pseudo-reality and prevent silly detailing. Again - if you put it in an opaque container that's on the caster.
Your example text is way too loose and open to various interpretations leading to rule wrangling along with unnecessary descriptive elements.

Pizza Lord |
PizzaLord wrote:...thanks. I know my rulez jargon can seem like a bear trap (as it is) and opaque at times as I'm not explaining everything or triviata.
That's fine, but for people trying to just and gauge a spell's power or use, or to see where it diverges (in the case of a spell you're tweaking, like twilight knife, it makes them wonder whether the damage is the same or not.
It's one thing to write. 'It deals 1d6 electrical (or 'flame') damage per caster level.' We can assume you meant electricity or fire damage. It's another thing entirely to suddenly write it as, 'Deals CL/2*d6 damage of the fire type and this damage is reduced by resistances to that damage the target has.'
We're gonna say, "Just write 1d6 fire damage per two caster levels!" I am not mad or anything, I'm not your boss. It just makes it hard to at a glance know if the damage has been altered. :p
Your example text is way too loose and open to various interpretations leading to rule wrangling.
It was an example, and can be tweaked as suits, I needed to make sure it had the word blank in it (rather than adding in a new line in the description). It could just as easily be 'Two blank parchment (1 gp ea.)' or even add in 'fine' or some other word to indicate these aren't normal 2 sp parchments.

Azothath |
no problem - people miss the details in things I write as it can be rather condensed. A lot of GMs are generalists and it takes a few readings for them to get everything.
I agree with Belafon that you have to read kineticist a few times to get how it works... lol. I don't think I'm that abstracted here.
I do like the idea of HP Howler letter... lol... but the kids never did that so it's a 3rd spell level spell or better and more complicated than this somewhat cumbersome spell with messages in a bottle or animal messenger animal couriers.