Undead Fortitude. If damage reduces the Undead Druid 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 Undead Druid drops to 1 hit point instead.

Spellcasting. The Undead Druid is a 1-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 12, +4 to hit with spell attacks). The Undead Druid has the following Druid spells prepared:
Cantrips (at will): [Primal savagery], [Thorn Whip]  

Multiattack. The Undead Druid can make two Longbow attacks. One of these attacks can be replaced with a Druid cantrip. (For lower level party’s give disadvantage on the second attack)

Longbow. Ranged Weapon Attack: +3 to hit, range 150/600 ft., 1 target. Hit: 5 (1d8 + 1) piercing damage.