I've been searching the net in vain for a long time now and got nowhere, well until I found this site. Here is to hoping you can help me.
Back when I was in Secondary school (UK) in the early 1990's I borrowed from the school library a fantasy style book. Now sadly I cannot remember much about it other than it had your typical "assembled group" of young boy/hero, a warrior, a magician etc etc. All I can remember of the book was when they fight the main villain/antagonist at the end the fight is desperate and the hero seems to think that his magician friend has been killed yet notices his hand twitching. Then a Demi-God appears who was summoned by the magician who was actually carving runes with his hand on the floor of the battle area.
I may be remembering wrong but I think the magician had a twin brother, the boy had/met a girl companion with a possible romantic link developing. They travel to the enemies castle/cave/domain and attempt to battle him and as said the magician summons a demi-god to defeat the evil antagonist. Any help would be greatly appreciated.
That is all I can remember unfortunately so any help, assistance or nudges in the direction of will be most appreciated.