@Lancefighter -
I feel like we're talking about a completely different game here.
If you honestly think that a Tristana with a Brutalizer and a BF Sword jumping into 4 enemy heroes would do absolutely anything but get destroyed, you're either thinking in pub terms, or you don't realize why Trist is pretty much never picked anymore competitively.
If you also think that a Katarina, with the farm equivalent to a Brutalizer and a BF Sword could kill 4 heroes at half health or more with just her Q, W, and E, you are also, sadly, sadly mistaken. In fact, the Katarina on the other team used all her skills in the same teamfight just before Khazix arrived! With even more farm, and with her full ultimate hitting Khazix's team, her damage paled in comparison to Khazix's, and also she didn't have the mobility he had to finish her kills off, because where she can "jump" one time, he can jump 4.
And yet here we are, arguing about a completely insignificant portion of khazix's play (collecting free kills his team set up for him)
You keep saying it was a set up, I think he was just late to the battle. You keep acting like any hero could do what Khazix did there, but I think you're completely wrong. With the farm Khazix had at that very moment, NO other hero (including Tryndamere, Kat, Morg, or anybody else) could not do that much AoE damage, while having that much mobility to chase anybody down who tried to get away. This is why Khazix is pretty much permabanned in competitive play, and when he's not, his team usually wins.
Trynd is bad, he's not used anymore. Mostly because his design is awful.
But we don't have to argue about it anymore really, I'm still waiting to hear what Khazix's weakness is. If nobody can provide a clear weakness to the hero, then I have no reason to think he's anything but completely broken.