This is the way I build Nyx Assassin. Nyx is a great ganking hero who can easily take out squishy Intelligence heroes, but if needs be he can be a pretty good support as well. While ganking, you wanna try and find pick offs as often as you can. The combo goes Vendetta Hit, into Impale, into Mana Burn, into Dagon if you have one. As a Support you wanna let your carry get all the last hits and try and use your stun to set up kills.