[quote=@Antarctic Termite]
After many years, Vowzra came to find her, only to discover that she had actually torn one of its pages. Vulamera was absorbed into the Codex in order to repair the damage, resulting in her demise.
[/quote]

It wasn't a very big secret, that. She did it ages ago when Lif was born and gave the torn bit to him. It wasn't an entire page, just a small edge of a page that she thought was insignificant at the time.