v.102 â Rise of Fellowship Update Notes

No, it should be rare and permanent.

By "should" i meant given that they've already clearly made up their minds on making them expire. Because they expire, they should be common.

Something tells me they are required to make them expire though since it isn't really their content. New monster book isn't technically theirs either but it's a fundamental system to any good game and it only hurts themselves to put a similarly crippling limitation on the monster book. This isn't so for familiar.