Magi mastered the usage of laws through knowledge and comprehension. Using their spiritual force, they manipulated elemental particles to form all sorts of spells. This was their path to power.
They didn’t stop at that, though. Along with comprehending laws, they also integrated other power systems into their own spells. This was what led to the glory of ancient times.
Leylin knew from the Scorpion Man’s memories that the creatures of the Icy World were famed for their strength and vitality. Arwen, who stood opposite him, had evidently inherited these traits.
Although Leylin was a bloodline Warlock, he still did not measure up in a contest against an actual ancient creature. Hence, as a true Magus should, he tried to shift the battlefield to one in his favour.
As in the words from his previous life, one had to match one’s strengths to their opponent’s weaknesses.