Nyx Assassin is a versatile melee agility hero. He is capable of fitting into numerous roles, including mid lane ganker, offlaner, and support.
In public matchmaking Nyx has traditionally been played as a solo mid, where he acquires a quick level 6 and then uses his ultimate to gank and snowball, although its populairty has declined with the advent of support Nyx.
Skills
Skill and max Impale first most of the time, unless you want to harass with Mana Burn straight away.
Skill Mana Burn second. You can also max it second if you're against a solo mid who is heavily reliant on mana.
Skill Spiked Carapace last.
Always get your ultimate, Vendetta (levels 6, 11 and 16) and look to gank with it as soon as you hit your quick level 6.
Your typical combo is Vendetta > right click > Impale > right click > Dagon > Mana Burn.
Items
Starting Items: a set of Tangos, Healing Salve, 3x Iron Branches, Circlet.
Early Game: Boots of Speed, Magic Wand, Null Talisman.
Core: Arcane Boots, Dagon.
Luxury: Blink Dagger, Ethereal Blade, Veil of Discord, Necronomicon, Drums of Endurance, Vladmir's Offering.
Optional: Bootle