Located inside the Grateful Boon treasure.
If this treasure has been looted prior to unlocking Protoform Synthesis for mounts, the schematic will be available at the same spot the treasure is located at.
Grateful Boon treasure
You need to pet all the animals on top of the mountain
5x Agitated Vombata
4xAgitated Cervid
3xAgitated Lupine
They are running around and will stop when you succeed with the pet cast
After you pet the last one the Tah Fen in the middle of the area will unlock the treasure
None the Wiser Guild 