She is one of the “Trio” of House Il'lerth, the three branchwych sisters who harvest the fallen lamentiri or life seeds of dead Sylvaneth, planting them within new Soul-Pods to bring forth treefolk. Her sisters Llane and Sylanna were slain and she was badly injured by followers of Nurgle. 
Using the Spirit-Song she travelling to sister Wyldwoods of her own Borcelann, Ithilia and Mer’thorn discovering how they had fallen to Chaos. With this knowledge she was able to save Borcelann Wyldwood from Skathis Rot, a Daemon Herald of Nurgle and then spread the word amongst the remaining Jade Kingdoms of how it was done. 
|I am Nellas the Harvester, of House Il’learth of the Heartwood Glade. I am bearing the lifeseeds of many of my house. Too many. In the name of the Everqueen, stand aside
~ Nelaas to the Outcast, Du’gath.