Lugh attacks the school while Arata and Mira are being held far away. Yui evacuates everyone in the school into her dream to protect them, and Levi sets out to fight alone. But Lugh is a demon lord candidate who has obtained a demon lord element.
I see. So basically, the reason is unknown.
Verstehe. Die Methode
ist also unbekannt.
Ya veo, ni siquiera tú debes saberlo.
Ya veo, ni siquiera tú debes saberlo.
Je vois.
Capisco, quindi non vuoi dirmelo.
Então basicamente é 
um método desconhecido.