After a battle with Merlyn, Green Arrow was injured and bleeding to death in the ruins of Star City. He along with Team Arrow, Connor Hawke, and Speedy spent months training with some of the greatest fighters in the world which lead them to Natas. Oliver has hired this renowned assassin as he wished to understand how killers such as Deathstroke think and feel, to absorb the "killer's lament".
When the training began Natas spends weeks beating the crap out of the hero, attacking and trying to kill him when he least expects it, and always fights dirty. He puts Green Arrow through a brutal trial of martial combat. Over time Green Arrow hones his body to perfection and transforms himself into a living weapon.