Core Formation Realm and an Extra...

After hearing that, Sister Orb analyzed the Twins' Dantians.

[Not bad... You two did well. This Last Stage of the Foundation Establishment took you a lot more than any of the previous stages. However, that was because you two didn't have enough time to wait for your Late Stage to mature appropriately.]

Sister Orb continued.

[Fortunately, there's no danger of a Universal Restraint approaching anytime soon, so you took your time to stabilize your foundations naturally. After you finished stabilizing your foundations, you had a lot of Rank Three Spirit Stones to use as well. So far, it seems like your foundations are in the best condition. As for the limit you talked about, I think it is already good enough.]