Russet Bufonid

To get [item=188810] you need to find [item=189471] in Zereth Mortis and bring it to the Synthesis Forge*, then collect reagents for the craft

How to get Schematic:

1. 
   
2. Inside the [item=187780] that you can get from [quest=64867] emissary Vilo NPS quest
   
3. 
   

Resources required to craft (all of them are zone related):
350x[item=188957] - drops all over the Zereth Mortis
[item=189174] - 300g from Vilo
[item=187633] - Can buy on AH or farm from specific mobs (check dropped by section)

* Synthesis Forge Prerequisites to be able to see a schematic & to turn it in & craft the Mount:
Complete 3 parts of the main campaign in the Secrets of the First Ones Forming an Understanding
Complete [npc=181397] upgrade [order-advancement=1904] => [order-advancement=1932] (to craft pets) & [order-advancement=1931] (to craft mounts)
Complete Protoform Synthesis quest to craft pets / Finding Tahli questchain & After daily reset The Lost Component & A New Architect to craft mounts
More detailed info can be found here: Synthe-supersized!
/way 70.18 28.60 Servitor Interface (Mounts Forge Location)
/way 61.97 58.93 Protoform Synthesis Forge (Pets Forge Location)
Right now you will need to complete the prerequisites to interact with the forge and turn in the schematic quests