The Thanatos Guild

S6 E16: Nyssa Al Ghul (recurring guest star KATRINA LAW) returns to Star City to warn Thea that a group of renegade League of Assassins members are planning to attack her. This group, led by Athena (guest star KYRA ZAGORSKY), is intent on finding a mysterious box that Malcolm left behind and will stop at nothing to get it. Nyssa helps Oliver come to a life-changing realization.