Following up on another post about Celtic-themed D&D races, I wanted to write a short paragraph about how each class fits into a Celtic-themed setting, but it wasn’t working. Each class fits very well as stated, but they need framing in context of Celtic society and legend, so here’s that instead. I'll start with religion and magic, and cover warrior culture later.
The details of historical Celtic religion are incomplete because they had no system of writing, and their myths mostly survive in folk tales and fairy stories, many written by Christian priests during the Dark Ages! In addition, some elements date back to Neolithic times. Stonehenge probably meant something different to the builders thousands of years ago than it did to the people Rome found and wrote about. We do know that the Druids were an integral part of their society, along with Bards. Since we’re talking about a fantasy setting, we have a lot of leeway and should always go for something engaging for players.
The Druids are the oldest and most pervasive religious force in Albion. They act as advisors to kings, give judgements in law, and see the will of the gods and spirits of the land. Youths with potential are trained for years in the ways of nature, the stories of the people, and legends of the supernatural. They are not priests who claim to act as the voice of the gods, but they are wise and learned enough to be the best counselors in all things mundane and supernatural. Because of this they are found among mortals and fey alike. The Gaels are still firmly entrenched in Druidism, but the Britons are split between the rural folk who remember the old faith and the few large cities where Imperial customs and religions are more dominant.
The Druids teach that the world has a mirror reflection called the Otherworld, where all manner of spirits dwell. The Otherworld is a place of magic, the home of the fey, and also the temporary realm of the dead. Druids also believe that mortal spirits reincarnate over time, and foul magic and undead that subvert that cycle are despised.
Individuals exceptional to actually have Druid class levels can guide natural forces around them with their spells and take the form of beasts. Sacred groves and standing stones are their places of worship, especially at solstices and equinoxes. People will be reverential of them when they wear their ceremonial white robes, even in cities where the Church of St. Cuthbert thrive. The spirits respond to each Druid differently, and players should work out with the group how their spells and Circle abilities are unique to their character. The shamans of the Picts and Saxons are mechanically similar to Druids, just with less formal training and social importance. They are more often a vessel for spirits to speak through.
Bards are short-changed in D&D. They are mocked as silly minstrels who sings songs while their allies fight. Bards are a part of the Druidic order and incredibly important to the Celtic culture. With no written language and constant in-fighting, the shared stories of the people keep their values alive. Bards are always welcome wherever they travel, and expected to share news and recount heroic tales. They wear bright colors of many hues as a sign of their training. The old Welsh wise men who pre-date Merlin were usually described as Bards. The spells and inspiration abilities of classed Bards are proof that the magic of the Otherworld lives in their songs and poetry, that they can remake the world around them with their art. The different Colleges are different roles Bards can play—sages, warriors, entertainers, and assassins. The Saxons have their own tales of glory and love of kennings (poetic descriptions of common terms) that thrives among their Skalds.
The spell casting abilities of the Ranger tie them to the Druidic order. In a land permeated with magic, it makes sense that warriors close to the land would learn some of its power. There are also Celtic heroes like Finn McCool who trained with Druids and Bards. Any character with nature-based spell casting should have a unique relationship with the spirits they gain their abilities from.
The Empire may be gone from Albion, but its influence still lingers. The largest cities have architecture, technology, and most importantly, new gods left behind by the foreign powers. The most prominent new religion is the Church of St. Cuthbert. The Church teaches the doctrine of Law conquering Chaos, through the spread of mortal civilization and the destruction of supernatural evil. Unlike the Druids, the priests of the Church have a rigid hierarchy and claim to be the voice of their god through religious texts and tradition. Outside of the cities, priests can be found as solitary missionaries trying to convert with talk and deeds. Other foreign religions can exist as wanted by players, but probably have similar structures. Their miracle workers, those with Cleric class levels, are holy warriors, healers, and direct expressions of their god’s will. Celtic or pagan Saxon gods (mostly similar to Norse gods) may imbue a champion with their divine power, but they are not part of an order. This allows for players to play with access to a broad range of Domains, but they need to be clear if their part of a civilized Cleric tradition or a pagan with mechanically similar abilities. This creates the divide between the New Church and the Old Faith that is important to Albion.
Arcane spell casters are outside the Druidic order but still get much of their power from the Otherworld. Their relationship with Druids will depend on whether they subvert the natural order when they use their magic. Warlocks have a patron who interacts with them and seeks to influence the mortal world through them. Sorcerers exhibit primal magic left over from the creation of the world. Wizards catalog magic into forms and patterns they can recreate.