The Restless Draugr is a 1st-level spellcaster, Its spellcasting ability is Intelligence (spell save DC 12, +4 to hit with spell attacks). The draugr has the following Wizard spells prepared:

Undead Fortitude. If damage reduces the draugr to 0 hit points, it must make a Constitution saving throw with a DC of 5+the damage taken, unless the damage is radiant or from a critical hit. On a success, the draugr drops to 1 hit point instead.