Ra's al Ghul
The League of Shadows members that were loyal to Ra's al Ghul used a ritual that involved Bruce Wayne's blood to bring Ra's al Ghul to life when they think that Barbara is not living up to her potential. Following a duel where her abilities show her different outcomes like her getting stabbed or Tabitha's neck getting slit, Barbara relinquishes the abilities which fully restores Ra's al Ghul. Afterwards, he later pays a visit to Bruce when Selina is around where he states that an upcoming fire in Gotham City will shape him into a Dark Knight...if it doesn't consume him first.