Arthur patiently waited for the perfect chance to strike. With the Spatial Master present, he couldn't attack whenever he wished, he needed to be precise and see how fast the reaction of the enemy is.
He decided to only attack at the 5th Eft attack, which was launched by three efts, which charged simultaneously from three different directions. Despite the supposedly surprised attack, most of the group were careful and were not surprised by the appearance of the three giant creatures.
Albeit being on full alert, some of them were affected by the technique of the efts' eyes and were paralyzed, which rendered them useless in the incoming battle.