Infernal or Eredar

Infernal is the language of devils. Knowing that many devils would deal with mortals for their souls to join them, The devils declared that their primary languge called Eredar (Called infernal by outsiders) would the the seven hells' common language.
To non-native speaker, infernal may appear to have a kind of underlying condescension. Metaphor is an integral part of the language, and words usually have multiple meanings depending on context. Few among the devils' people speak the common tongue, and fewer speak it well.

Writting system

Phonetics

Infernal is a slow language which falls off the tongue like molten lava slowly oozing out of a volcano. Its a heavy and weighty speech. It flows together through more of a g/l/h/m dominated language rather than harsh k's or c's.