Echidna used Thunder Beam on Femradiel, but she also used Mana Shield to protect herself while she was working. Eventually, the whole barrier was surrounded by ice, and slowly, the coldness emitted by that massive amount of ice began to spread inside the effect of Chronos' Ring. It took a while, but Echidna eventually noticed what Femradiel was planning. It was a weird tactic. Still, it seemed highly effective against spells like Mana Shield.
"I see… you want to create a space where the effects of your ice magic can massively damage my Mana Shield," Echidna said. "Still, do you think you can do it? I can survive outer space for quite a while and with this type of spell, I can probably stay there for years without running out of mana."
"That is impressive, but you will die in less than one hour here," Femradiel said.