Last Updated on November 7, 2023
Large Aberration, Lawful Evil
- Size: Large
- Creature Type: Aberration
- Alignment: Lawful Evil
- STR 21 (+5), DEX 9 (-1), CON 15 (+2), INT 18 (+4), WIS 15 (+2), CHA 18 (+4)
- AC: 17 (natural armor)
- Hitpoints: 18d10+36 (135 avg)
- Saving Throws: CON +6, INT +8, WIS +6
- Speed: 10 ft., swim 40 ft.
- Skills: History (+12), Perception (+10)
- Proficiency Bonus: +4
- Senses: 120 ft. of Darkvision and 20 Passive Perception
- Languages: Deep Speech, telepathy (120 ft.)
- Challenge Rating: 10
Amphibious: Able to breathe air and water.
Mucous Cloud: While underwater, the aboleth is surrounded by transformative mucus. A creature that touches the aboleth or that hits it with a melee attack while within 5 feet of it must make a DC 14 Constitution saving throw.
On a failure, the creature is diseased for 1d4 hours. The diseased creature can breathe only underwater.
Probing Telepathy: If a creature communicates telepathically with the aboleth, the aboleth learns the creature’s greatest desires if the aboleth can see the creature.
Aboleths have several actions available to them in combat.
Multiattack: The aboleth makes three melee tentacle attacks.
Tentacle Attack: Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 12 (2d6 + 5) bludgeoning damage. If the target is a creature, it must succeed on a DC 14 Constitution saving throw or become diseased.
The disease has no effect for 1 minute and can be removed by any magic that cures disease.
After 1 minute, the diseased creature’s skin becomes translucent and slimy, the creature can’t regain hit points unless it is underwater, and the disease can be removed only by heal or another disease-curing spell of 6th level or higher.
When the creature is outside a body of water, it takes 6 (1d12) acid damage every 10 minutes unless moisture is applied to the skin before 10 minutes have passed.
Tail: Aboleths can also attack with their tails (+9 to hit, 10-foot melee range) for 3d6+5 (15 avg.) bludgeoning damage, though this takes their whole action.
Enslave a creature three times a day. Any creature within the aboleth’s visual field targeted by this ability must make a DC 14 Wisdom saving throw or be magically charmed by the aboleth until either it dies or the two are no longer on the same plane of existence.
A telepathic bond is also formed that works over any distance so the aboleth can maintain control.
Enslaved creatures can’t take reactions but can repeat the saving throw if they take damage or if they’re more than a mile away from the aboleth for the first time in a given 24-hour period.
The aboleth can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The aboleth regains spent legendary actions at the start of its turn.
Detect.The aboleth makes a Wisdom (Perception) check.
Tail Swipe. The aboleth makes one tail attack.
Psychic Drain (Costs 2 Actions). One creature charmed by the aboleth takes 10 (3d6) psychic damage, and the aboleth regains hit points equal to the damage the creature takes.
Finally, aboleths have lair actions they can take on initiative count 20 when they are in their lair. These actions can take one of three forms.
- The aboleth casts phantasmal force (no components required) on any number of creatures it can see within 60 feet of it. While maintaining concentration on this effect, the aboleth can’t take other lair actions. If a target succeeds on the saving throw or if the effect ends for it, the target is immune to the aboleth’s phantasmal force lair action for the next 24 hours, although such a creature can choose to be affected.
- Pools of water within 90 feet of the aboleth surge outward in a grasping tide. Any creature on the ground within 20 feet of such a pool must succeed on a DC 14 Strength saving throw or be pulled up to 20 feet into the water and knocked prone. The aboleth can’t use this lair action again until it has used a different one.
- Water in the aboleth’s lair magically becomes a conduit for the creature’s rage. The aboleth can target any number of creatures it can see in such water within 90 feet of it. A target must succeed on a DC 14 Wisdom saving throw or take 7 (2d6) psychic damage. The aboleth can’t use this lair action again until it has used a different one.
The region containing an aboleth’s lair is warped by the creature’s presence, which creates one or more of the following effects:
- Underground surfaces within 1 mile of the aboleth’s lair are slimy and wet and are difficult terrain.
- Water sources within 1 mile of the lair are supernaturally fouled. Enemies of the aboleth that drink such water vomit it within minutes.
- As an action, the aboleth can create an illusory image of itself within 1 mile of the lair. The copy can appear at any location the aboleth has seen before or in any location a creature charmed by the aboleth can currently see. Once created, the image lasts for as long as the aboleth maintains concentration, as if concentrating on a spell. Although the image is intangible, it looks, sounds, and can move like the aboleth. The aboleth can sense, speak, and use telepathy from the image’s position as if present at that position. If the image takes any damage, it disappears.
If the aboleth dies, the first two effects fade over the course of 3d10 days.
Aboleths are ancient creatures. Existing since before the gods, they ruled the pre-divine universe until they were cast down… and they haven’t forgotten.
Aboleths have perfect memories and can pass memories down through the generations. That means every aboleth has the combined perfect knowledge of every aboleth that came before it.
Moreover, aboleths can’t actually die. Killing one only destroys its physical form. Its spirit returns to the Elemental Plane of Water where it can create a new body for itself.
These creatures are essentially immortal geniuses with access to a vast amount of knowledge, a grudge against the divine, and an intense desire to be worshiped. The campaign practically writes itself!
Aboleth tactics can be complex and fighting back even more so. The range of abilities and lore behind an aboleth means that countering them requires understanding exactly what they can do and how they do it effectively.
Follow the lore and the tactics below, however, and you can give even veteran parties a real run for their money.
Aboleths are deeply intelligent creatures with millennia of knowledge and experience at their command.
All their actions will be extremely tactical, and if they can gather any intel on the party before the fight, they can tweak their strategies to the players’ weaknesses.
Thus, aboleths will often try to maneuver a situation such that they can win before combat even starts by manipulating a situation or tricking the party into acting on bad intelligence.
Aboleths can’t be killed, but death is still an inconvenience. Being banished back to the Elemental Plane of Water means that they lose control over anyone they’ve enslaved.
That could be several hundred followers, and an aboleth will hate to lose such an investment.
An aboleth will play it a lot more cautiously than your average tentacled sea monster. They’ll watch the party and gather intel as much as possible, and when the party invades their lair, they might not attack right away, if ever.
Moreover, a party is very unlikely to ever face an aboleth without followers. They may be able to engineer the situation to face the aboleth 1-on-1 as it were, but if the aboleth has any say in the matter, it’ll have minions. How many minions and how strong they are will significantly swing the difficulty of the fight.
Remember that an aboleth by itself is CR 10. That estimation always goes up with friends.
When gathering intel on an adventuring party, the aboleth will make use of its Detect legendary action to assess the party and try to guess who has the worst Wisdom save.
It might even try to Enslave a party member or two before the fight, making them into sleeper cells for the aboleth.
When combat actually occurs, an aboleth will primarily lean on its tentacle multiattack for damage as well as minions.
It will try to disease members and force them into the water. The aboleth is under no obligation to stay and fight for that entire minute the disease to take effect.
Once a diseased party member has died from suffocation or entered the water to be able to breathe, the aboleth will strike.
In the latter case, it can easily grapple an underwater party member and swim away with them entirely, capturing them in order to eventually convert them into a follower with its Enslave ability and an unlucky save.
D&D 5e parties excel at straightforward combat encounters that end with the party dead or victorious.
The aboleth will deny your players that luxury, and an encounter with one of these creatures will take several minutes as the aboleth repeatedly throws attacks at the players and retreats to await its disease and use its Psychic Drain ability to heal itself.
The aboleth’s Psychic Drain ability has no range, and so long as all the creatures it has enslaved remain within 1 mile of it, the aboleth could have thousands of creatures under its command (beyond 1 mile, many of the creatures will eventually make their saves).
That means that, given about a minute and a half, an aboleth can heal itself to full as long as it has enough followers with enough hitpoints to burn through.
Finally, during the entirety of combat, the aboleth will be sending telepathic messages of temptation to the players.
If any player responds in their head and the aboleth can see them, the aboleth will be able to tempt the player with their greatest desire, potentially bypassing the need for magical control.
A Note on Lair Actions
Aboleths are careful, and the 1-mile limit on controlling their followers means that they usually stay in their lairs.
That means that most of the time an aboleth encounter will take place on the aboleth’s home turf where lair actions add another layer of complexity to the fight.
While making use of lair actions is a no-brainer, you should actually be pretty particular about what order you use them. If you’re unfamiliar with lair actions, I strongly recommend checking out this article that goes more in depth.
Assuming you know how they work, let’s look at how your aboleth should use them.
In combat, an aboleth will usually rotate between grabbing players with water and using its ability to channel psychic damage to anyone in the water close enough to it.
The former control ability is particularly useful for dragging adventurers into traps if not into the water with the aboleth itself. Remember that, once in the water, an adventurer is vulnerable to being grappled and stolen away.
However, prior to combat and occasionally in combat, the aboleth’s ability to cast Phantasmal Force will come into play.
This spell forces an illusion on a target that makes the target believe some phantasm is real to the point of being able to take 1d6 psychic damage from the phantasm whenever such damage would be appropriate.
This has a myriad number of uses in traps, tricks, and temptations — far too many to go into here. Bear in mind that aboleths have excellent darkvision and might be able to see the adventurers before they know it is there.
As long as it can see them and they haven’t successfully made a save in the last 24 hours against the spell, the aboleth can target players with repeated phantasmal forces for uses limited only by your imagination.
Fighting an Aboleth: Countertactics
If you’re fighting an aboleth, don’t go in the water. However ready you think your party or your character is for underwater combat, you aren’t as ready as the aboleth is.
Keep a Detect Disease up to make sure you can cure the disease within a minute with a quick spell. If you wait too long to cure it, you’ll have to use a 6th-level spell slot to save your friends.
Use Protection from Good and Evil to prevent the Aboleth from mind controlling your party members.
Many of the aboleth’s abilities rely on sight to function. Deny it that with the spells Darkness, Fog Cloud, or Blindness/Deafness, and you’ll be able to protect yourself effectively.
Forcing the aboleth out of the water is the biggest advantage you can give yourselves.
You might be able to do this by freezing enough of the water in the area so that the aboleth has to come onto land or is denied access back into the water.
However, control spells like Telekinesis might be more effective at dragging the aberration out of the ocean.
The spell Control Water might also help with exposing the aboleth.
The 4th-level spell Banishment can also be extremely effective here; if the aboleth fails the save, you can force it permanently off the Material Plane until it can find its own route back.
This will also free anyone enslaved by the aboleth, destroying its cult.
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Growing up I spent most of my time reading, so when I first started playing RPGs in middle school and got a copy of DnD 3.5’s rules I loved their collaborative take on storytelling. These days I like to use RPGs to develop my creative problem-solving skills as well.