Eldritch Horror at Abyssal Depths
Lurking in the depths since 1st edition D&D, aboleths are the legally-distinct Lovecraftian horrors of the deep we’ve all grown to fear. Aboleths are basically great big psychic lamprey eels lurking in the aquatic ruins of their former civilization and plotting on how to take vengeance on the dumb land dwellers. So, how should you run them in your adventures? And what are you supposed to do when your DM decides to throw you into the deep end with them? Don’t breathe the slime and stay out of the pool as we go through everything you need to know.
Aboleth lore is really Lovecraftian Cthulhu lore wearing a legally-distinct mask. They’re terrifying fishy monsters that used to rule the world and can psychically influence the unwitting fools up on land. Basically, if you think of something about a “Deep One”, you’re right on the money or pretty darn close to a feature of the aboleths. We’ve got ancient sunken cities, check. Bizarre and utterly alien psychology, check. Eldritch horror, check. Loads of creepy tentacles, check. And finally, brainwashed fish people, check, and double check. They’re also intensely smart and have a bizarre form of racial memory. New aboleths literally remember everything their parent remembered, and for functionally immortal beings that have been around since earliest recorded history they can hold a grudge or conduct a scheme for a very long time.
Physically their descriptions have waffled back and forth between more eel-like and more squid-like over the years, but generally they look like big lamprey eels with a bunch of bonus tentacles. If you’re not familiar with lamprey eels, they’re a real-life creature that looks like it was born in a nightmare dimension. Essentially eel-like but with a big jawless sucker mouth filled with teeth.
Aboleths are fundamentally psionic and have a nasty habit of mentally enslaving the “upstart races” (everybody not an aboleth) to do their bidding. This wouldn’t be too much of a problem if it weren’t also for their trademark aboleth mucous. Just like the hagfish, these monsters exude buckets of slime that surround them in the water. Touch or breath the slime (from attacks or simple proximity) and you risk catching the aboleth disease. The nasty goop quickly transforms you into a fishy shadow of your former self and forces you to only breathe underwater while you’re affected. Aboleths use their slime to force their slaves into the deep, and often their aquatic cities are crewed by helpless diseased surface dwellers.
There are technically variant aboleths (great big nasty ones and some wimpier young forms) from previous editions, but mainly 5e just has the OG eel to work with. They’re formidable threats, compounded by the fact that the most likely place to find one is in their lair deep in the ocean.
Large aberration, lawful evil
Armor Class 17 (natural armor)
Hit Points 135 (18d10+36)
Speed 10 ft., swim 40.
STR DEX CON INT WIS CHA
21 (+5) 9 (-1) 15 (+2) 18 (+4)15 (+2)18 (+4)
Saving Throws Con +6, Int +8, Wis +6
Skills History +12, Perception +10
Senses darkvision 120 ft., passive Perception 20
Languages Deep Speech, Telepathy 120 ft.
Challenge 10 (5,900 XP)
Amphibious. The aboleth can 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.
Multiattack. The aboleth makes three tentacle attacks.
Tentacle. 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. Melee Weapon Attack: +9 to hit, reach 10 ft. one target. Hit: 15 (3d6 + 5) bludgeoning damage.
Enslave (3/Day). The aboleth targets one creature it can see within 30 feet of it. The target must succeed on a DC 14 Wisdom saving throw or be magically charmed by the aboleth until the aboleth dies or until it is on a different plane of existence from the target. The charmed target is under the aboleth's control and can't take reactions, and the aboleth and the target can communicate telepathically with each other over any distance.
Whenever the charmed target takes damage, the target can repeat the saving throw. On a success, the effect ends. No more than once every 24 hours, the target can also repeat the saving throw when it is at least 1 mile away from the aboleth.
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.
An Aboleth’s Lair
Aboleths lair in subterranean lakes or the rocky depths of the ocean, often surrounded by the ruins of an ancient, fallen aboleth city. An aboleth spends most of its existence underwater, surfacing occasionally to treat with visitors or deranged worshipers.
When fighting inside its lair, an aboleth can invoke the ambient magic to take lair actions. On initiative count 20 (losing initiative ties), the aboleth takes a lair action to cause one of the following effects:
- 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.
Using an Aboleth as a DM
Aboleths make great BBEGs (big bad evil guys) to cap off tier 2 adventures or really nasty mid-bosses to throw at tier 3 adventurers. They’re notorious manipulators and schemers, perfect for being the force behind any number of nefarious plots you may want to cook up for them.
When planning your final fight with the aboleth your first concern should be location. A fight with an aboleth near the surface will be a lot easier than a fight at the bottom of the ocean. Generally speaking, the further from dry land you go the harder your aboleth fight is going to be, especially if you take the players down into the aboleth’s lair.
The next thing to consider is how your players are going to deal with the aboleth disease. It is almost guaranteed that during a fight with an aboleth one or more of the players will be afflicted, and therefore stuck living underwater until the players can get together some 6th level healing magic. You can use this as a plothook to propel the players towards the next adventure to get some healing, but otherwise you should provide them with some handy heal scrolls or a friendly healing NPC as part of the rewards for the fight. You don’t want to end up splitting the adventurers semi-permanently into air breathers / water breathers if you can help it.
Finally, a good chunk of the aboleth’s abilities revolve around mind-controlled thralls. I recommend providing your big baddie with a few hapless NPC puppets at the beginning of the fight to provide some variety and tasty hit points for the aboleth to siphon off in a pinch.
Fighting an Aboleth
No swimming for 1 hour after spotting an aboleth, kids, stay out of the pool. Seriously, the name of the game when fighting an aboleth is staying dry. If your DM gives you the choice, don’t go swimming and fight the big eel from dry land. If you’re lucky enough to stay dry while fighting it, use range as much as possible and just keep out of the water.
There’s a good chance your DM will have you fighting on its turf though (err, surf), and once you’ve been afflicted with the aboleth disease you’ll basically be stuck in the drink for the rest of the fight (at least). You’ll be more vulnerable to lair actions and numerous other attacks in the water, so if you’re the healer try to stay within range of anybody in the water and generally just try to stick together. The aboleth will have the full advantage of mobility and splitting up will spell doom for whoever gets isolated.
The best bit of advice I can give is to keep a hand free to punch your friends with unarmed strikes (yes really). It only takes 1 hit point worth of damage to get another saving throw against the enslavement and a good old, unarmed strike does a whopping 1 point + your Strength modifier. For most characters this is the least damaging way to wake everybody up once the aboleth starts psionically enslaving people.
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Last updated: January 27, 2019
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