The Field Guide Badge is earned by teaching or leading an activity at a Monstro Camp. (Teach an art or craft, run a game, or demo something Ranger related.)
It is earned, and is not for sale. (Though one could trade to get one.)
There is a single level of the Field Guide, and it can be earned just once currently. (Though you can certainly run more than one event at different camps.)
Field Guide was introduced at Monstro Camp Prime 2018.
The Field Guide Badge is worth 99 points, far more than most other Spirit Badges.
Guiding others is something that Rangers do.
This is an ultra-rare badge.
See the full Badge Directory.