When Femradiel gathered the mana of everyone, she decided to attack. The alliance members kept sending their mana to her, but the ice coffin Ymir had prepared was already closing up, and Femradiel saw Ymir already passing through it. Another option that they had was to create a hole in any direction using the ice she was preparing, but she doubted that it would be large enough to let everyone pass at the same time, even while using Teleport.
Before letting all the mana explode instantly, Femradiel wished that she could get stronger using the same greed that Ryan had. Now that she thought about it, his endless desire to build a future where he would be satisfied was probably what made him win all those impossible battles.