Monster of the Month: Spell Leech

Each month, we’ll give you a new monster to use in your 5e game. This month, we give you the Spell Leech. You can download the description and stat block of the spell leech here.

There is one type of creature that every novice magic-user should learn to fear — the spell leech. These bizarre creatures resemble flying purple leeches with toothy maws and transparent stomachs that glow with the magical energy on which the spell leeches have fed.

A spell leech feeds by biting and latching onto a spellcaster, such as a wizard, sorcerer, or cleric. It then slowly drains its victim’s ability to cast spells for as long as it is attached.

Spell leeches can often be found congregating in places of arcane or mystical power, such as conjunctions of ley lines, ancient ruins, or the sewers beneath arcane colleges.

Magical Hunger

Spell leeches are driven only by their hunger for magical energy. The hunt magic- users, and will only attack a non-magic-user in self- defense. They also have no particular desire to kill: once its victim is drained of spell slots, the leech usually detaches and sets off for its next meal.

Bane of Mages

Spell leeches are particularly dangerous to spellcasters, and not only because of their ability to steal spell slots. They are particularly resistant to spells and magical damage. They even have the ability to negate a mage’s protective abjurations, making their prey vulnerable to their leeching bite.

Speculated Origins

Mages have long researched the spell leeches in order to find a way to better understand this threat. There are a few theories as to the origins of these creatures. Some scholars believe that they naturally evolved from regular leeches exposed to intense magical energy. Others believe that spell leeches were a deliberate creation of a mage-hating group or individual. A few sages have suggested that these creatures are as old as magic itself, and exist as a natural mechanism to keep magical energy in balance, but these theorists are often ridiculed by their peers.


Spell Leech

Small aberration, unaligned

Armor Class 17 (mage armor)

Hit Points 45 (10d6 + 10)

Speed 0 ft., fly 50 ft. (hover)







10 (+0)

18 (+4)

12 (+1)

18 (+4)

12 (+1)

12 (+1)

Skills Perception +4

Senses blindsight 60 ft., passive Perception 14


Challenge 5 (1,800 xp)

Leech Spell. A creature that starts its turn with a spell leech attached to it and has spell slots must succeed on a DC 15 Constitution saving throw or lose a 1st level spell slot, as if they had used it to cast a spell.
If the creature has no 1st level spell slots remaining, it loses a spell slot of the lowest level in which it has remaining spell slots.

Magic Armor. The spell leech can cast the mage armor spell on itself at will.

Magic Resistance. The spell leech has advantage on saving throws against spells and other magical effects.

Sense Magic. The spell leech senses magic, including the presence of spellcasters, within 120 feet of it at will. This trait otherwise works like the detect magic spell.

Spell Absorption. Whenever the spell leech takes a spell slot from a spell caster using its Leech Spell ability or when it succeeds on a saving throw against a spell, it regains 1d10 hit points, plus 1d10 additional hit points for each level of the spell slot absorbed or used to cast the spell above 1st level.

Spell Damage Transfer. While attached to a creature and hit with a spell attack, the spell leech takes only half the damage dealt to it (rounded down), and that creature takes the other half.


Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) piercing damage plus 10 (3d6) psychic damage, and the spell leech attaches to the target. The spell leech can detach itself by spending 5 feet of its movement. A creature, including the target, can take its action to detach the spell leech by succeeding on a DC 11 Strength check.

Bonus Actions

Negate Magic Armor. The spell leech can dispel any spell that provides a magical AC bonus to a creature such as mage armor or barkskin, as if the spell dispel magic had been cast.