Rush Bottle, followed by Dagon. Bottle gives the mana and regen he needs to perform his combos. Dagon is rushed to extend his combo damage, as NA is normally used to take out a specific target hero that’s a problem for the team. Nerubian Assassin is totally flexible in what items to get. After your Dagon, feel free to get either Heart for tanking hits or Guinsoo for the disable. Or both if you are in a position to farm for it. Boots should be upgraded to BoT late game. If the game continues to extend any longer, get Butterfly and Manta Style for DPS.