Unlike what is presented below the Glaistig of Scottish legend was often a benign ... or at the very least neutrual spirit that took the form of a young and beautiful woman. In some stories the Glaistig was found to be a blood sucking ghost that would lead men and travellers (typically also men) to dark places to feed on them.
The Glaistig presented below is a much, much darker creation as I wanted to set it apart from other Ghost-Type Creatures.
The woman appeared behind them, plain but attractive. El’s companion – ever the noble knight – stepped toward her, a warning of the dungeon’s dangers on his lip … El’s warning wasn’t quick enough and in a moment the knight was dead and the woman vanished only to reappear mere inches from El’s outstretched hands.
Type: Undead, Ghost
Hit Dice: 7
Armor Class: 3
Attacks: Touch (2d8 + Level Drain)
Saving Throw: 9
Special: Immune to Sleep, Charm Hold, Normal Weapons. Intangible, Ghost Step
Move: 12 [36’]
Challenge Level/XP: 11/1,700
Immune to Cold – Due to its nature as a vengeful spirit the Glaistig can move through solid matter at half its normal speed.
Ghost Step – Instead of normal movement the Glaistig “flickers” in and out of sight every 3 feet adding an extra 3 feet to her movement ratio.
Glaistigs are the undead of innocents who were murdered or killed for dark rituals and magics. The energies that the innocents’ deaths and blood were used for inadvertently bind the soul of the victim to the Mortal Realms and driving the soul into inescapable madness.
Glaistigs lack much of the intelligence they once had and are driven by their madness. Typically Glaistigs are encountered in groups at sites in which dark rituals took place or evil wizards made their homes.
Armor Class 17
Hit Points 48 (7d8+3)
Speed 30 feet
Str 8 (-1) Dex 16 (+1) Con 16 (+2)
Int 6 (-2) Wis 8 (+1) Cha 3 (-4)
Alignment Chaotic Evil
Skills Stealth +6
Special Senses Dark Vision 60’
Immunities disease, hunger, poison, sleep, suffocation, thirst, cannot be frightened, charmed, put to sleep,etc.
Damage Resistance to all weapons save those of silver make.
Ghost Step – Can walk through any solid object at half its normal speed.
Melee Attack – Energy Drain. +5 to hit (reach 5ft; one target). Hit 14 (2d8+3) necrotic damage, and if the target fails a SC 16 Constitution Saving Throw, until the target completes a long rest, its total hit points drop by the amount of damage it received during the attack. If the target reaches 0 hp as a result of this attack it dies and its soul is consumed by the Glaistig causing it to regain hit points equal to the target’s hit dice. Once killed by a Glaistig the target cannot be resurrected or reincarnated.