Prefer

'Gosh, I don't know how much longer Lau will have to finish all this. But I have to be prepared in case the vampires come to attack here. They move quietly, surely they will enter by sneaking in.' Yaris took a deep breath. 'But it is possible that they attack openly, even though that is not their characteristic.'

 Yaris used her magical power to slowly build the barrier, at least she had done something that could help the defense of the castle. No matter how small his contribution in helping guard the palace, it will still be very helpful for everyone in the palace.

 Meanwhile, Lau is struggling to destroy the magical dimension. Lau with his power that can be related to seals, can change or tamper with any seal made by others.

 Lau's magical power is rarely possessed by others. People like Lau are typical of people who have 'forbidden' magical powers.