Spoiler for Chapter 154:
Teresa's full power utilizing the Quick Sword = atomizing Priscilla.
It is pretty amazing from both ends here, Priscilla basically spent every battle trying to get herself killed, but her own power left her unable to die even when her body was blown to pieces.
On the other end, Teresa utilizing her full power in combination with the Quick Sword technique was necessary to even make her death possible.
By the looks of things Priscilla was almost on the level of Cell (DBZ) when it came to her healing abilities, so annihilating her utterly was the only way to accomplish this.
I'll wait to see the last chapter to give any final thoughts on the series, but I definitely like Claymore as a whole and it will be missed.