Homebrew
Spellcasting. The Shadowfell Gnome Mage is a 7th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 14, +6 to hit with spell attacks). It has the following spells prepared:
Undead Fortitude. If damage reduces the Shadowfell Gnome Mage 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 gnome drops to 1 hit point instead. Shadow Stealth. While in dim light or darkness, the Shadowfell Gnome Mage can take the Hide action as a bonus action.
Shadow Bolt. Ranged Spell Attack: +6 to hit, range 12 sq., one target. Hit: 18 ( 4d8 ) necrotic damage. Necrotic Grasp. Melee Spell Attack: +6 to hit, reach 1 sq., one target. Hit: 13 ( 3d8 ) necrotic damage, and the target must succeed on a DC 13 Constitution saving throw or be paralyzed until the end of its next turn.