Cannot for the life of me think of the name of what I’m pretty sure was a three book series, here’s what I can remember:
There’s a barbarian invasion of some more civilised nations, a few of the civilised cities have colleges of magic. Magic users are called mages and in desperation one city summons a barrier of demons to surround themselves and have to sacrifice people to it every day to keep it up, this makes the demons so strong they can no longer be controlled.
There’s also dragons who are actually in an alternate dimension/plane/whatever and humans meet and talk to them at some sort of inter dimensional crossroads, the dragons are really angry about the demons thing. The main characters convince a few of the dragons to come help them and they cross in to the main world through a portal tunnel they have to defend from demons, the dragons are trapped there at the series end because the portal shuts.
One of the main characters finishes the book defending the dragons from would be poachers.
I’m afraid that’s about all I’ve got, I know it ain’t much but I’d appreciate any help anyone can provide.