A powerful, skeletal, undead creature who casts spells to defend itself. In life, a lich was a powerful spellcaster. When it becomes a lich it is now an unholy creature whos power in casting spells is amplified into a veritable killing machine, via its majicks.
The lich only pointed at his enemy. A beam of dark energy exploded out of his finger and hit the fighter in the chest. He died on the spot.