During the events that led up to the Battle of Biel-Tan, Lathriel sought to close the Webway portal on Ursulia known as the Obsidian Gate to spare her home craftworld from an invasion by the daemons of Chaos.
She failed in this effort and was sharply reprimanded by her sister as a result.
Lathriel later chose to join the Ynnari just like her twin.
- The Gathering Storm - Part Two - Fracture of Biel-Tan (7th Edition), pp. 4-101
- White Dwarf 33 (May 2019), pg. 48 (Image)