At Imbolc the Fianna gather around large bonfires (although a reasonably sized fireplace will do in a pinch) to perform one of their more powerful rites. Until recent years, almost all Fianna septs performed the Imbolc rites. Today, a good number of septs still perform the rite, though only the Fianna of the British Isles rigidly keep the tradition. Although the Imbolc rites almost always take place at a sept's caern, they do not absolutely have to be performed there.
At sunset the bonfires are built up and lighted to the rhythms of Celtic music. The mood is usually intense with anticipation, and many Fianna claim to find their perceptions involuntarily slipping into Penumbra throughout the preceding day. As the flames begin to light up the night sky, the ritemaster tells the tale of Fionn mac Cumhail, the First Friend of the Fianna, and the greatest among their Kinfolk. After the first tale is finished, the ritemaster moves on to several more classic Fianna ballads and stories involving the fair folk. As she speaks, the ritemaster carefully grinds up a small number of faerie seeds with a mortar and pestle. These seeds, which have been gathered during the Fianna's occassional forays into faerie trods or the Aradian Gateway realm, are powerful indeed. Mixing the seeds into a potent home-brew, the ritemaster invites each Garou present to partake of the newly created spirit-brew.
As each Fianna scoops up a mug of the brew, she calls out a stanza of poetry, a short riddle or a few lines of song as an offering to Gaia at this time of awakening. Once all have filled their cups, each of the Fianna raises her cup and drinks in turn to Fionn mac Cumhail, the new cubs of the Fianna, and their friends of faerie (some Fianna have hypothesized that this is actually a toast to the past, the present and the future of Gaia, but most Fianna dismiss this hypothesis). Drinking three times deeply, the Garou step sideways into the Penumbra. There (unless the rite fails) they find at least one dweller of faerie awaiting the Garou, and quite often a large number of the creatures. Very often the type of faeries discovered awaiting the sept provides an omen for the coming year, and so the Fianna are always concerned if one of the dread and sorrowing bane-sidhes awaits their coming. Why the faeries agree to participate in these rites is unknown, for no Fianna consult with them on the matter. However, the Garou assume the faeries made a bargain with one of the Fianna's ancestors and honor it to this day.
Once in the Penumbra, the Fianna follow their faerie escorts through the Near Umbra to the border between the Fianna homeland and Arcadia. There, every Garou partakes in racuous hunt, straining his senses to their utmost, as clues and signs of Gaia's will and her needs in the coming year are often found on Imbolc. The clues are always vague, although this seeming could have to do with the Garou's profound inebriation and the effect of their proximity to faerie. It is also said that some Fianna have been known to lie with faeries on this night, but this may be mere rumor and boasting.
As the night wears on the Garou collapse one by one, worn out by their spiritual journey. They each awake in the morning. Rarely is a Fianna lost during this rite. On the occassions when a member of the sept does not return, the Garou mourn; but they also believe that the Garou was taken in by the faeries, and that such an alliance may give the sept an advantage should the fey return to Gaia.
Source: Werewolf Storytellers' Handbook