Arrow: Season 6, Episode 16

6 - 16: The Thanatos Guild

Nyssa Al Ghul 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, 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.