Lost Skills

Lost Skills (ロスト・スキル) are the skills and magic which considered lost after demon lord died.

History
After the Demon Lord died, there was a huge shift in mana in the atmosphere. The source of magical energy in all living beings. This means spells are far weaker today than in the past—because of the rapid decline in the amount of mana. And that's why many high level magic got lost.

Skills

 * Double Chanting
 * Giga Flare
 * Ultimatum Zero