Although the mage who worked for Alexei couldn't use that mist a lot, he certainly decreased the difficulty of the battle. Thanks to the steel walls, the monsters didn't invade the city. The only real troublesome monsters were the vampiric harpies since they could make rain magic over the soldiers and drink their blood to heal their wounds and recover mana.
"I guess their mage is specialized in Area of Effect spells… That's one of the things I need to learn. I wonder if I can copy him just by observing…"
Unlike Yuki's skills, that guy used his mana to attack, so it wasn't all that different from what Leon used to do. That being said, Leon didn't feel the need to learn an Area of Effect spell now that he had the ring of gravity. Although he still would rather use a skill than rely on an item forever…