As intimidating as the Nightwalker seems, it isn't without some pretty glaring weaknesses. Chief amongst these is its low intelligence, wisdom, and charisma scores, which make it susceptible to certain control spells. Spells like Command Undead and Control Undead are unlikely for the Nightwalker to resist due to its low charisma and intelligence scores and lack of immunity to being charmed. These spells are good choices, but Banishment is the real winner. Not only will this allow you to end a fight with the Nightwalker immediately, but it will also send it back to the Negative Energy Plane, saving whichever hapless fool decided to set foot there and release the Nightwalker in the first place. If spells aren't your forte, the next best thing is a fighter or barbarian with a magic weapon and many, many hit points. If you've got a good constitution, many attacks a round, and a reliable way to get past the Nightwalker's damage resistances, you can take one down before it does much lasting damage to the party. Remember that a drawn-out fight isn't in your interest, as the Nightwalker excels in wasting your resources and weakening you from repeated exposure to its debilitating effects. If all else fails, make sure to have an escape plan. The Nightwalker is fast and incredibly mobile, but it's dumb and not very observant. Use stealth to your advantage or spells that provide invisibility to escape if things look like they're going badly. Always keep its ability to kill you instantly in mind, and don't utilize unnecessarily risky tactics if you can help it.