Kha'Zix or Rengar?

lorewise if kha'zix is fully evolved he can kill rengar easily no matter who attacks first

I think Kha'zix will win because of his adaptive powers

I think it depends on who sees who first, if Rengar manages to land an ensnare on Kha, Kha is dead, if Kha lands a pink where he is, Rengar is SUPER DEAD, so, yeah, Kha has more chances of winning this one, specially because he has extra chance of winning against solo targets.

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http://www.hiveworkshop.com/forums/pastebin_data/qd31zm/ThePhoenixTalon.jpg

In game, Kha'Zix dies easily by Rengar (most of the time), but in lore Kha can POTENTIALLY outmatch them. It depends on what he's eaten since their last encounter.

At first glance rengar looks like the protagonist and Kha'zix like the villain of the story(because kha looks and acts more evil than rengar and rengar has a bit of an underdog feeling to him since he pretty much lost their first encounter),so I'd say Rengar would be likely.

However I think that Kha'zix winning the fight would be more interesting.

I mean what happens if Rengar wins?He gets a trophy and would probably become depressed again that there is no worthy prey anymore(maybe he'd go somewhere else to search for them) and maybe they could make a story about rengar trying to find out about his roots,where he came from and so on. However the thing is that the whole story about "feels empty after achieving his goal and searches for new opponents" could also be done with Kha'zix and the "tries to find his real family" could be done before their final battle.

However if kha'zix wins,they could actually let him evolve in the lore(they could make stories how kha'zix consumed certain beasts to evolve his W,E and R and through the consumption of eating rengar he could get his evolved Q),which would be interesting to see.