Druidic

Druidic is a guttural ancient language spoken mostly by those who follow the Green Father as clerics or his chosen Druids. Many of his creations also speak the tongue and use it to leave messages for one another by inscribing it upon trees or stones. 
The Clans of Solstein spoke Druidic due to their founder favouring it over the common tongue that he feared was a slave language. Despite this many Solsteiners also learned common to aid in their raiding but spoke Druidic as their mother tongue.