I've just started a new campaign in second edition, which I'm also fairly new to. (I try to keep up with the books and reading but this is my first REAL game with the system)
As the title states, I've been attempting to create a conversion of the Cipher class from pillars of eternity (basically a Psychic Gish that builds energy [called focus] for spellcasting by dealing damage with weapons) for use in this campaign, but I'm having some difficulty converting some major portions of the class.
Base proficiencies and progression are simple enough, as this is, at a glance, an occult version of the Magus, to which end most of the proficiencies would likely match up (Master in Unarmed/Simple/Martial weapons, Master in up to Medium armor, and Master in Occult spellcasting.) Saves could be argued, and skills would likely be of a similar amount depending on the key ability score.
The challenge in my eyes starts with the first mechanic of the class, the Soul Whip. In the video game, Soul whip is a buff that applies to all your weapon attacks while you aren't at full focus, granting roughly 20% increased damage and converting a portion of your damage dealt directly into focus points, which are then spent to cast spells. Obviously the percent damage is right out, as that would just get annoying and the typical damage numbers in 2E don't justify it's use, but I'm not really sure what to use in it's place. There are a good number of class based damage buffs to draw inspiration from, but none of them is a perfect fit for the nature of the ability. Ideally it would be something that adds a noticeable but not overwhelming amount of damage to weapon attacks, that ideally would scale up the more damage your weapon dealt. The least mind-wracking idea I had here was a flat damage bonus that scaled with the number of damage dice your weapon dealt. This would keep damage fairly in line with other melee-type mechanics, and also provide a fairly direct way to generate the points for spellcasting, which could be as simple as "gain an amount of spell points equal to the damage dealt by your soul whip."
Next, and perhaps even more challenging, is the nature of the spellcasting itself. A "mana" system is quite separated from the way normal spellcasting is done in 2E, but I think the focus on spell levels as the scaler for spell power rather than caster level provides a fairly simple place to start; simply present a point cost for each level of spell (something like 5 per level, going from 5-50.) This system would preclude the use of actual spell slots, simply allowing for a highest level of spell as levels increased and likely working off a spell repertoire as an alternative form of spontaneous caster.
Another way to do this, and a way that perhaps appears more thematically coherent, is focus spells. Especially as focus points are a term used by both the class and 2e itself, trying to blend them together could certainly be an effective and efficient way to streamline the conversion, but not one that doesn't have its own issues. Focus spells, as written, don't really have a way to scale in the way cipher spellcasting is supposed to, as they automatically heighten to half your level and always cost 1 focus point each. In addition, trying to jury rig soul whip to generate 2e focus creates a whole wave of issues relating to focus spells from other classes now being rechargeable simply by hitting stuff. With all that in mind, focus spells seem like the wrong way to go.
There are absolutely more parts to the class to consider in converting, but these stood out to me as the most fiddly ones. If anyone has any advice or suggestions for making this, please let me know!
There is a *wide-open* space for "casters that don't use spell slots" and "gishes that don't use spell slots" that pretty much hasn't been explored in the rules at all. We have hopes that we'll get it some day, but it's not here yet, and it's not likely to come all that soon. (Like, if we're really lucky, we might be able to playtest one some time within the next year and a half, but I wouldn't be ton it.)
As such, there *are* no comparable equivalents to the thing that you're trying to suggest. Unfortunately, this makes the process of balancing quite a lot harder. Basically, you can't balance inputs. You can only balance outputs. Basically, write up the class with the mechanics that you think would be fun to play and satisfying, and then sit down and crunch the numbers about how effective they are in a bunch of different ways as compared to the various other classes out there. Figure out what the cipher is supposed to be good at and not good at, make sure that they're not Just Plain Better than any of their comparables, and so forth.
Worth noting that trying to balance on output is hard. It takes a lot of effort, and a lot of system mastery - both to understand what the comparables are and why, to know where the really important numbers to balance around are, and to know where the potential exploits might be when combined with existing abilities. That need for system mastery also means that it's going to be far harder to do it as someone who's new to PF2.
One question arises, though. The answer is going to be pretty significant as far as how easy or hard it's going to be to balance this thing. Why do you want to create a Cipher class on one of your first few times GMing?
This sounds a little bit like the mechanics for the Psychic. What was it, Unleash Psyche I think? Basically, you enter it to get some minor benefit (I think it was amping spells) and drawback and after so many turns it unlocks a greater ability you could utilize. [basically giving you an ability you work up to being able to cast, not something you could blast out on your first round of combat each time]
Almost seems like what you want is to Gish the Psychic base, go into Cypher stances, and instead of amping spells, it would provide a minimal energy bonus to your melee strikes, and after so many rounds of successful strikes your stance gets enabled, and you basically get access to that stance's finisher which might be kind of spell-like. Each stance might offer a finisher spell. Might even offer a cantrip spell associated with it that can be cast as long as you have passed the first round of your stance, potentially for instance.
I'm not familiar with the Cypher class itself. So I don't know exactly, and I imagine you might be used to having a larger variety of spells you might cast on a whim after 'charging' and my proposal kind of dictates what spell (or small set of spells, cantrip and finisher) that you are likely working towards, at the start of your stance.
However since you are opening up to casting spells more quickly recovered than traditional Focus requirements (10minutes) you probably need to limit the casting a bit for balance reasons. One way of doing that might be to have them commit to what they are casting earlier, when they enter the stance.
Then you class can collect 'stances' they learn as they level up they choose new stances, and may even have stances that have minimum levels where they can be chosen. And some stances may have finishers with Heightened effects based on their 'spell level' again half the character level round up.
In addition to your Cypher stances, you might have the class have access to focus spells that might provide some 'utility' options, and might provide some flexibility outside of the straight combat process. They might also have access to certain other cantrips. [or have them always have access to the Cantrips that their stances allow, but only have them auto-heighten (otherwise always cast as a 1st level spell, or always cast at 1/2 normal spell level) and they only cast their cantrips at normal spell level when having at least one round of stance under their belt already.
Again granting them some flexibility, but at a cost and making them hopefully not overshadow some other class in their flexibility.