SOLVED. Old Sci-fi book about soldiers on a border patrol, fighting monsters with lances that shoots magic [s]

[Beatrix]

I'm looking for a book I borrowed from the library close to 15 years ago, so 2000 or 2001.
But I've always thought that library only stocked old Sci-Fi books, so it might be older.

It is an Adult book, no romance as far as I can remember.
Paperback with the following on the cover:
A man on a horse (white, I think), with a Lance pointed at a multi-colored, scale monster - a Basilisk. The type that has multiple legs and claws, not the snake thing.

The book is about a young man, who was sent to the army (to be kept out of trouble). His company was assigned to ride border patrol and kill all the monsters. I vaguely remember a Wall that they needed to protect...
One of the more fierce monsters was a multi-color/rainbow Basilisk. And some type of mutant large cat.

The soldiers used a Lance weapon that could shoot magical energy. But the amount of time they could shoot was very limited.
The main character could use magic (he needed to hide that fact) and he often pretended to use the Lances magic to shoot, but actually channeled his magic though the Lance.

He could also use his magic to heal himself and others. But it wasn't anything flashy or a miracle instant heal. More a speeding up of normal healing.

This book is not a stand alone, I'm fairly sure its a trilogy.

So... any clue what book this is?

[Lobstergirl, au gratin]

The Ring of Fire? Cover looks promising although people shelved it as YA or children's.

[Lobstergirl, au gratin]

There's also The Lure of the Basilisk with cover:

[Jeremy]

Based on your description, I think you might be talking about Magi'i of Cyador and/or Scion of Cyador by L.E. Modesitt Jr.. Those two titles are a two-book story arc within the Saga of Recluce series.

[Beatrix]

Thank you Jeremy!
Magi'i of Cyador by L.E Modesitt Jr. is the book I am looking for.

And Thank you Lobstergirl for the other two suggestions.