After 6/7 attempts of using the BLACK EYE ORBI finally managed to beat Lautrec. I ended up luring them to one of the first staircases and as soon as they came up one by one I hit them back off the ledge. That way they kind of took turns in coming at me and the mage's spells usually got stuck in the staircase. After about 3 3-hit combo's Lautrec was done for. Hurray!