Although different magical traditions have the same abilities to learn powers and cast spells, they use draw upon different types of spirits when they use the Summon Ally power.
As in Sprawlrunners and Summoner’s Circle, spirits have defined power levels. I’ve additionally given them explicit names, to make it clearer:
A mage can only summon spirits of their own rank or less.
A mage doesn’t need to do anything to “learn” new ranks of spirits as they increase their own rank. On their 8th advance, when they move from Seasoned to Veteran, common spirits become available to them automatically.
All mages can summon watchers - little more than a blob of magical energy squished into form by the mage’s will. Although the true nature of spirits is hugely debated, most mages agree that watchers are not “summoned” as such but rather created on the spot.
Hermetic mages can summon elementals of the four classic elements: fire, earth, air, water. Each spirit exists at lesser, common, and greater levels.
Compared with other spirits, elementals are somewhat… dreary. They lack intellectual curiosity and are easily confused by unexpected situations. They also seem to have no capacity for boredom, and will carry out the most rote of repeated tasks without seeming complaint or irritation. Hermetic mages treat them as mere servants, and elementals seem content in that role.
Elementals have stats and abilities as per Sprawlrunners.
Shaman spirits take the form of nature spirits. Shamans treat them with great reverence and respect. Nature spirits are more independent than elementals but can be capricious, and sometimes have their own ideas and agendas.
Nature spirits have stats and abilities as per Sprawlrunners. Note that nature spirits can ignore 2 points of casting penalties when in their home environment.
Note also that Sprawlrunners RAW uses “Focus” as the spellcasting skill for spirits. For technical reasons related to FoundryVTT, it’s easier to rename this to “Magic”, so it’s the same name as everyone else uses.
Many other magical traditions are what magical researchers refer to as attuned summoners. These are characterised by having a much smaller roster of spirits to draw on than other summoners, but these spirits are much more closely bound to the summoner and typically demonstrate greater loyalty than other spirit types.
When they first take the Summon Ally power, attuned summoners automatically gain access to two spirits of lesser rank. As they increase their own rank to Veteran and then to Heroic, they gain two common spirits and then two greater spirits.
These spirits can be created freely by the player.
Once a character achieves Initiate status (by taking the Edge), they can take a downtime action to journey to the metaplanes and bond with a new spirit type, of any rank they choose. At that time, the player can create a new statblock for the new spirit type. Afterwards, they can summon that spirit as they please. See downtime actions.
They can repeat this process until they have a total of four spirit types at each of lesser, common, and greater rank. At that time, if they undertake an Attune action again, they must remove one other spirit from their roster to make room for the new one.
In addition to the above, there are other types of spirit that are strongly associated with various magical traditions. There are no game mechanics for these currently.
There are also traditions associated with dark magic: