- Can just be a problem the player has to deal with. I think people are hesitant to do this, but it’s a real possibility, and one that opens up play space that’s not normally utilized. A flower mage who can’t be away from their garden for more than three days is interesting.
- Allow fast travel between a designated garden and the outside world. This can be munchkined, but maybe that’s okay. I imagine a twenty pound stone that the flower mage lugs around with them that serves as their return marker, but naturally that would allow for things like sending the stone by post in order to skip travel. Sometimes it’s okay to break the game like that.
- Allow the flower mage to carry their garden with them. There are a few ways that this could work, whether that’s extradimensional spaces, miniaturization, or having the garden be tucked into a personal demiplane that gets attached to the soul or visited only astrally or something. Again, it would be important to think about the knock-on effects of any of those solutions, but I love knock-on effects, so that’s appealing to me. You could also possibly have this ability cost connection (or a spell slot equivalent).
Because the pustule mage carries around their arsenal at all times, they’re much easier to transition to TTRPG, where lots of travel is the default. The natural limits to the magic system (how much the body can handle, connection to the processes, available body space) also help to justify some of the mechanical limitations that wizards are often saddled with (spells known, spells per day, limited metamagic). In fact, I’m pretty sure that there were one or two prestige classes in 3.5 D&D that followed a fairly similar model, and if you wanted to, you could just go use those and maybe get either mechanical inspiration or a prestige class that matches the flavor.
In terms of making pustule mages de novo, the biggest thing to consider is whether or not you’ll be using drawbacks. Drawbacks are generally anti-fun (and discouraged by a lot of modern game design), so long as we qualify that drawbacks are different from limitations, but they’re the clearest way to model a pustule mage’s pustules. For every “pustule” that a pustule mage has, they get a malus of some sort, whether that’s to social interactions because they’re disfigured, to physical actions because they’re weakened, or some lesser or greater malus that presumably depends on the flavor and power of the pustule in question. The big things to watch out for, as always when using drawbacks, is making sure that the drawbacks actually are drawbacks, and that there aren’t strict no-brainer synergies that everyone uses because the bonuses are good enough that they cancel the maluses out without any actual issue.
(Though on the other hand, I really like used and lived-in magic systems, and it’s neat to have pustule mages at the Vervainium have a codified set of viruses, bacterial infections, induced skin disorders, etc., which they enter into at specific stages of their training and once they’ve passed through medical inspection. If you did that, which will be canon to Worth the Candle once the worldbuilding doc finally gets published, then you would want to balance around it, so that (for example) at level 3 of the pustule mage class, you get strains X, Y, and Z, which acts as more of a flat increase to your power.)
In terms of flavor, there are two major points.
The first is that pustule mages are experts at their own bodies. Here, I think mostly about diabetics who have to constantly measure their glucose levels and make sure that they have the proper sugar intakes, or bodybuilders who measure out their meals to the gram. Some people get super obsessed with the microbiome of their gut, or their vitamin levels, or something else, and that kind of dedication to the physical self is part of what makes for a successful pustule mage. A pustule mage will know whether their skin is producing more or less oil than normal, whether they’re a touch anemic, whether they’re retaining water, and naturally, the specifics of every single disease/virus/malady that they’re currently channeling, along with their interactions. If they use herbs, pills, or other methods to mitigate the effects, then they know the effects and side effects of those as well as is able. (Bodies are all different though, and on Aerb more than on Earth, so there’s some guesswork, cargo culting, superstition, etc. going on, as there is with perfectly normal people on Earth who get really into total nonsense.)
The second is that pustule magic is super gross; the grosser you can make it, the better. If you were adapting a spell like Summon Swarm, you would have the swarm bursting forth from an orifice, or have each rat pop out of an individual clogged pore, or something similar. Go watch some popping videos, if you need inspiration (if you don’t know what those are, you probably don’t want to). While the effects of the “pustule” don’t have to be gross themselves, as with the fireball stand-in used in Worth the Candle a few times, the “casting” of the pustule should be in some way, and anti-gross spells should be avoided. Pustule magic isn’t one of the core magics in Worth the Candle, so there’s lots of room to make things up.
- Druids can do anything that the DM lets them do, where the DM is trying to optimize for the most wondrous, magical feeling possible. This should generally preclude repeating the same effect too many times in a row or systematizing druidic magic. The big problem here is that what’s going on mechanically is that the player is checking with the DM before casting every spell, or trying to find creative ways to do the same thing two or three times, which from a ludonarrative standpoint has dissonance written all over it. You could make a better version of it, which is that druids can do anything and they’ll lose their connection to the locus if they violate the DM’s rules, but that’s just a question of default-no or default-yes and I don’t know how much of an improvement it would be. Probably works well if the player is good at not doing power creep and/or good at roleplay.
- Druids have their rules changed every once in awhile. From a game design perspective, this is a little tricky, since you don’t want to strand a player in an unfamiliar system … though here, you kind of do. It’s also tricky because making a morphable system is difficult to balance and difficult to make fun, and I don’t have any clever ideas for how it would be accomplished except through combinatoric explosion. It’s also a little bit out of flavor, since the player is attempting to divine the rules, rather than just going with the flow, not trying to systematize, etc.
- Druids say fuck the rules, and that’s their power. Here, I think you would take a bog standard druid, then graft on completely different resolution mechanics, something from a different game entirely. This would be a bit more of a meta approach; part of the point of druids is not putting things into these ordered categories, but they’re not necessarily about avoiding any and all frameworks, so maybe the right thing to do is simply to have the druid off playing their own game that interfaces with the primary game in some weird and (at first) novel way. Everyone else shows up with dice, but the druid gets a deck of cards, or a Jenga tower, or a Rubic’s cube, or something weird that still kind of works, but is ineffable to the others and has weird interactions. I think I like this one the best, mostly because it’s flavorsome.