There isn't a lot of Birthright specific stuff in the DM Guild, but there is a lot that with a little tweaking, could fit a BM Campaign in many areas of the world. One that could enhance a campaign in Cerilia in terms of adventuring would be the Chime and the Grandmother Druid from the Wayward Fey supplement from the DM's Guild.

Chimes

Rumored by sages versed in the realm of the sidhe and shadow to be in service of the mysterious archfey known as the Minstrel, chimes are creatures to be found near areas where the Shadow World pushes against Cerilia, and warn those that are in danger of crossing over to the dread realm.

Before the taint of Azrai, the chimes were whimsical creatures that wore bright red slippers, but now the colour has leached out of them and appear a faded, lifeless pink. The bells that ring when they open their mouths now have an otherworldly, dissonant quality.

Grandmother Dryad

In the deepest recesses of the forests of Cerilia, tales told by skalds say that there are trees that are so ancient that they were first blooming when the humans first set foot on Cerilia. The most venerable of these trees have given rise to the bastions of the tracts known as Grandmother Dryads.

On Cerilia, is it rumored that there are only 5 of these powerful fey in existence, and they are only to be found in provinces that have a source rating of 7 or higher.

The regions of Cerilia were it is rumored that Grandmother Dryads hold sway is as follows -

- Boerenbach, eastern Rohrmarch
- Ras Mhin, northern Khourane
- Kauth, west Grabentod
- Barrow Woods, northern Giantdowns

The fifth was said to be in Nys Annwn, but the “evil presence” that took hold recently may have meant the end for the Grandmother Dryad of the realm.

For the Grandmother Pine, her attendants should be normal bears from the Monster Manual and a number of fey in her service.