After Oliver Queen, the original Green Arrow, was bleeding nearly to death in the ruins of Star City (victim of a sneak attack by Merlyn the Dark Archer), Ollie, Connor Hawke, and Mia Dearden spent months training from some of the greatest fighters in the DC Universe including Natas.
Ollie uses Natas' resources to play the stock market, robbing several disreputable corporations of over a billion dollars.
Natas leaves Oliver Queen and his friends with a parting gift – a squadron of some of the world's deadliest assassins – and they have all been assigned to kill him.
For the next two hours, Ollie races about the island playing cat and mouse games with the hired killers.
[1] Ollie is now prepared to return to Star City, partially encouraged by a second note Natas left that leaves him a sword to include as part of his arsenal (while also asking him to remove the hat from his costume).
Natas responds by indicating that he is prepared for Deathstroke to teach his last student (Green Arrow) a lesson in failure.