Everything in the world has a 'time limit'. Nothing is eternal.
Even for those deemed as cursed, immortal or even the Gods, time limits exist for everyone.
Some may not be the standard type of 'time limit' that one would think of, but nothing truly lasts forever.
For the Goddess known as Velouria, that time limit was the Will of the Abyss.
Sooner or later, the expansion of the Abyss would've taken her life if the Gods failed.
When the sealed Abyss Lord of Old, Miralith, taps into the powers of time, she interferes with this time limit.
That's the key goal of the ritual performed by Selen when she 'summons' Miralith.
A barrier is formed around the target and within that barrier, time slowly comes to a halt. Once time is fully halted, the target is removed from the flow of time and erased.