Through the slow-motion view, Jack could see that just as his Sword of Light hit, Eldingar's hands were about to come down, bringing the doom of countless lightning balls down at him. At this time he cast Arcane Turbulence.
In his perception, his spell formation was forming at a normal pace. However, under an outsider's perception, the runes on his magic staff were formed at five times the normal speed. Hence, the spell was cast in less than one second. Jack didn't stop, he continued to cast Ice Ring. Although the boss was floating in the air, it was floating very low, the Arcane Turbulence and Ice Ring could still hit it.
Without stopping, Jack also cast Energy Bolts and Mana Bullet. All four spells were cast at almost the same time due to the Dragon's Eye effect. The two latter spells needed travel time to reach the boss, while the first two struck at a faster rate, almost instantaneously.