Auto-translated
In general, it should be noted that the demons of Ashan are primarily inclined not towards dark magic, but towards primal magic, as they were created by Urgash, who in turn was born from primal magic, as was his sister, Ash.
Primal magic appeals to Ash or Urgash, the primal dragons, and is associated with the spiritual matter born in the Void. It can draw magical energy from the spirit world into the material world (and vice versa) and manipulate the space-time continuum (to preserve or disrupt it). Primal magic can enchant an object (endowing it with a magical "soul"), animate a golem or skeleton (bind a spirit to a lifeless material form), open a gate between the material and spiritual worlds, etc.
Primal magic is preferred by the servants of Ash and the followers of Sar-Ilam (mages, necromancers, blind brothers, dragon knights...), but also by the servants of Urgash (demons and sorcerers).
In essence, "opening a gate" is a form of primal magic that opens passages between dimensions.
Perhaps it would make sense to place primal magic in the guild of mages for the demon, and by the way, then it would be possible to send him through the fire warriors