Himmel Soan wasn't concerned by Roams's achievement. He had shut Atlantis off with the shield, and no one could get out. Once he recovered a tiny fraction of his strength, he could destroy the entire Atlantis.
But something else he hadn't expected happened. Roams started working on Himmel Soan's shield. Once more, he succeeded.
Using the top-grade essence stones as the energy source, he mimicked his shield and built a smaller one around Himmel Soan.
Of course, Himmel Soan wouldn't be trapped inside forever. It would only create a little more trouble for him. He needed ten times more spiritual essence to destroy it, about 1/100,000 of his spiritual essence.
At first, he only needed a month to recover his energy. But now, he needed ten months. Luckily, he absorbed a few essence stones in between, which sped up his recovery, and he was able to break the shield.