When the depraved alpha Deucalion started recruiting for the Alpha Pack, Kali accepted the offer. Kali went on to murder her all of her own pack to join, and was to do the same to Julia.
Julia was ambushed by Kali in the reserve near Beacon Hills, California, then was severey savaged by the alpha. Julia was slashed in the face then knocked unconscious. However, due to their relationship, and believing Julia was harmless, the alpha couldn't bring herself to deliver the killing blow. She was left to die as Kali, her friend-turned-enemy walked away.
Though she was on her deathbed, in a feat to survive, Julia with sheer determination, managed to crawl to the local nemeton.
It was common knowledge the nemeton no longer held power, but Julia knew of the death of a virgin that had occured a few months earlier in the root cellar of the ancient tree: Paige Krasikeva who was mercy-killed by her werewolf boyfriend Derek Hale to save her from a more painful death. That single death had granted the tree stump a spark of power again.
Once Julia found the magical tree, she was able to harness that spark to keep herself alive. She was able to hold on to life just a little while longer until help arrived. Stilinski, then a deputy, found her.
Julia was brought to Beacon Hills Hospital. The same day, hundreds of birds began flying through the hospital into the walls, the windows. The animals, due to Julia's druid status, were sacrificing themselves for her.
Julia swore bitter revenge on Deucalion and the Alpha Pack, particularly Kali and overtime nothing would dissuade her from this goal, swaying away, then outright abandoning her role in maintaining the balance of nature. To this end, Julia choose to wait until the next lunar eclipse, when werewolves everywhere would be powerless.
Over the intervening decade, she went on to orchestrate and committ many more animal sacrifices. In doing so, using her druidic talents, she imbued herself with superpowers. Because of her self-serving whilst committing these sacrifices, as well as Kali's attack, Julia's appearance was left horribly disfigured, she used her talents to give her glamor, to disguise herself and changed her name to Jennifer Blake.