What Jack used was the Suppression Crystal dropped by Themos after he was slain. The crystal required a close range of ten meters from the target.
It was lucky that this archdemon was underestimating them. It simply stood in one place and focus on burning a hole in the dome's wall instead of dealing with them. This allowed Jack to safely get close enough.
The suppression crystal shone a bright light. The archdemon seemed to realize what Jack was doing but it was too late. Its haughtiness and Jack's time domain slowed its response. The light from the crystal enveloped it. It roared as it tried to fight the item's effect but even it had to succumb to the system's rule.
The archdemon's physique didn't show any meaningful changes, but Jack's mana sense detected a huge reduction in pressure emitted by the archdemon's presence.