The event begins a seemingly random length of time after the following conditions have been met, and can only occur once per game:
- Kha'Zix has used all three evolution points (level 16 minimum)
- must be at 5 stacks.
- All members of both teams must be alive at the same time. 
Each champion is assigned to kill the other and the first to achieve this claims victory and is rewarded (assists count). The event can only occur once per game.
- Rengar must kill Kha'Zix first to become the ultimate hunter (assists count). Rengar stalks Kha'Zix, his greatest prize, and the one beast to have escaped him. If Rengar is victorious, his is replaced with an item called the , which provides a 6th stack for his Bonetooth Necklace. If Rengar is successful, he gains a buff with the title . If he fails, he gains a buff with the title .
"This twisted monster has evaded me for too long. I will have his head!"― Rengar
- Kha'zix must kill Rengar first in order to become the ultimate predator (assists count). Kha'Zix is ready to devour Rengar, his greatest prey. If Kha'Zix is victorious, he gains a fourth evolution point, which allows Kha'Zix to evolve all of his four abilities. If Kha'Zix is successful, he gains a buff with the title . If he fails, he gains a buff with the title .
"I have grown and adapted since I took his eye. I will feast on lion!"― Kha'Zix
- When the event begins, there is a chime and players receive a "Quest Received" notification similar to the Mark of the Conqueror quest.
- The event can only occur once per game. If both teams have a and , the event will begin for the combination which meet the conditions first.
- The event will not begin until has used all three evolution points. As these are attained by ranking his ultimate, , level 16 is the minimum requirement.