Them and the chimera. All three became mana stones once they were dead.

...Not that it was easy killing them all. Each part of the chimera was attacking independently, along with both the witches... There were some really close calls.

[Don't ask him how many of those close calls were him, specifically, it's fine,,]

But anyway, once we killed all three of them, we found the moonstone was inside the chimera. So from there we just had to purify it and then we were done.