They are priestesses who sometimes practice sacred prostitution. It is not the first time that I see a character built around sacred sex work in OSR publications. This is a subject that can easily be problematic but I guess that it can also be used in a mature and respectful way. In the case of the Galli, this is again associating trans characters with sex work, but at the same time sex work is a part of the history of trans people and sex workers are also part of our community, I don't think that they should be erased. I played Satareh, a houri custom character class (a sacred prostitute) up to level 4 in the Ultan's Door campaign and I really appreciated this character, her role as a sex worker did not really come up during play, as our adventuring mostly happened outside the city but playing her made me think about how sex work could be handled in play.
Some guidelines to handle sex worker characters in a campaign:
- Lines and veils should be discussed with the player (and the group).
- The player should always be in charge of the sex work of their character, they need to be the one who decide to initiate it or not.
- The character can be tied to a temple or a brothel but they also need to be autonomous and be able to leave when they want. Their temple or brothel should generally be a positive network of contacts. There can be issues or problems to deal with but they should be optional and the affiliation should not be used by the GM as a excuse to coerce or abuse the character or to impose things on them.
- Humanize the NPCs sex workers and patrons, give them quality, flaws and relationships. Some of them may have problems that the PC can decide to get involved with or not.
- Be careful not to shame the character for their sex work or to gratuitously joke about it at the table. Some NPCs may have a bad opinion of sex workers but don't make it the default reaction.
- If you use the trope of the troublesome client, be careful not to remove the agency of the character, give them opportunities to handle the situation in their own way and give them means of ending or exiting the scene if they wish.
- Never use rape as a threat. There is so many other ways of depicting a troublesome client and other kinds of troubles to explore.
- If for some reason pregnancy or sexually transmitted infections come into play, always warn the player when there is a risk so that they have a choice of taking that risk or not. I would personally advice to discuss these when you first talk about the player's lines to see if these risks should even be on the table. When they happen, give the character various options to handle the situation.
- Try to avoid tropes like magical pregnancy, or again discuss them with the player and if you decide to explore them give various solutions and be careful with the character agency, don't impose this kind of tropes on the character, always present them as a choice.
GALLI as character class (by Fiona)
Who are they: castrated individuals who dress in luxurious robes, attractive headgear (crowns, laurel wreathes, or Phrygian caps) and excessive makeup. Their hair is long and their features feminine. They have knives, bronze shields, and tympanum and dance ecstatically. They are preceded by frenzied music and wafts of heady incense. They bear a representation of their goddess atop a donkey. They perform for money. Because of the edict against castration of a citizen, they are drawn from the ranks of low born and foreigners. Sometimes they practice sacred prostitution. The object of equal measures of scorn and religious awe.
Why are they: they wander around and perform blessings (a shield dance over newborns, blessing crops to be fertile as Attis represents the life-death-rebirth cycle of crops) and tell fortunes. The actual operations of the cult are opaque (it is, after all, a mystery cult).
Domains: the boundary between life and death, the wild (particularly birds of prey and lions), frenzied dancing, mountains and stones in general. In chthonic ritual practice can contact an ancient race of smiths/magicians who can work metal, teach the secrets of mathematics and literacy and bestow magic; they will also witness oaths and bind them.
How is one initiated: the only requirement is the devotion necessary to castrate oneself in a fit of divine madness during the 'Day of Blood' (March 24) in symbolic mourning for the temporary death of Attis. Then you become a mendicant priest and perform for the glory of Attis & Cybele.
 Galli are in various sources referred to with masculine pronouns, feminine pronouns and 3rd gender pronouns sometimes pegged to if they have castrated themselves.
Starting HP: 1d6+4
HP per level / resting: d6
Armor: bronze shields
Attack Damage: 1d6 / 1d4 unarmed or improvising
- Gain advantage to CHA tests while dancing or playing music.
- Gain advantage to INT tests while bestowing knowledge of metallurgy, mathematics, agriculture and literacy.
Once by day they can:
Once by divine favor they can:
- Sacred prostitution: when offering your service to a community test CHA, on a failure people avoid you (for different reasons), on a success you gain (level)d6x10 coins for the day, some rumors and a advantage for your next WIS test.
- Fortunes: name someone and test WIS, on a fail you bestow disadvantage to a random attribute, on a success you bestow advantage to a attribute of your choice. The disadvantage or advantage will trigger the next time this attribute is tested by that person.
- Shield Dance: while dancing you cannot attack but you gain advantage to defend against attacks, after d6 rounds of dancing you enter a battle frenzy and gain advantage to attack alongside a extra attack until the end of the fight.
Once by divine favor they can:
- Witnessing a Oath: when someone swear something you may declare that you witness the Oath, if the person break their Oath they will gain disadvantage to all their tests until they try to rectify their oath or ask you to “divine” their penance. (NPCs will simply fail at everything)
- Bless with fertility: take a turn to bless someone or something with fertility. Test WIS, on a natural 20 what will grow will be full of life but you must describe a monstruous feature that the gods bestow on them. On a failure you must declare that the gods do not approve the blessing. On a success you can divine a natural feature or trait of what will grow. On a natural 1 you must describe a divine feature that the gods bestow on them. (The blessing do not cause pregnancy, it only affect fertility)
- Replace a random encounter roll with a encounter with a lion. This lion will be neutral toward the Galli, test CHA to befriend it, on a failure the lion will leave and the Galli gain disadvantage to her next CHA test, on a success the lion will remain with the Galli until he fight once for her.
- Commune with the dead: test CHA, on a failure the dead bestow a bad fortune upon you (like the fortune ability), on a success the dead will answer d6 of your questions. Undeads will return to their normal behaviors after chatting.
- Contact Cthonian beings: test CHA, on a natural 20 you awaken a grumpy cthonian monster, on a failure d6 ill intended bitter cthonians will meet you, on a success you summon d6 helpful cthonians, on a natural 1, d6 cthonians come to bestow a gift from below the earth. The cthonians take d6 turns to arrive.
- Summon the Ambrosia of Cybele: personally gather honey, grapes and sacred herbs, bless them to transform them into ambrosia. When blessing them chose a effect: heal 2d6HP OR restore lost charisma OR work as divine Hormone Replacement Therapy (changes still take time).
(You can accumulate one favor by level)
- Being castrated (you can start play with one favor).
- Convert followers to worship.
- Observe the holy week of Attis being pledged to Cybele.
- Make a sacrifice of a ram to Attis (Criobolium) or a bull to Cybele (Taurbolium).
- Ritually sacrifice the testicles of a potent animal.
- Observe minor holidays organized around the import of Cybele's worship.
- Flagellation and frenzy demonstrating devotion.
- Give solid agricultural advice in line with the religious calendar.
- Dying and being reborn (earn 1d6 favors)
Roll to see if attributes increase, roll twice for WIS and CHA.
Random Cthonians Table (d6)
- Dwarfs or Gnomes covered with dirt and roots.
- Armored molerats people (or other burrowing animals)
- Blind morlocks or troglodytes.
- A cyclop and the assistants they crafted.
- Fossilized nymphs.
- Mad Geomancers.
Cthonian's Gifts (d10)
- Gem or magical stone
- Petrified body part
- Key to a secret passage
- Helm or shield
- Earth song dagger
- Statuette of a cthonian monster
- Crystallized bones or creature
- Perfume or balm
- Jewelry or erotic item