You’re sitting at the table. Your party’s Paladin is talking about justice. The Cleric is praying to a sun god. Then there’s you. You aren’t praying. You aren’t even really "serving" in the traditional sense. You’ve just tapped into a frequency that shouldn't exist, a signal from a being so massive and ancient that it doesn't even know you’re there. That is the core vibe of DnD Great Old One patrons. It’s not about a deal with a devil or a pact with a fairy. It’s about cosmic horror. It’s about being a flea on the back of a god-sized entity that dreams in geometry and whispers in static.
Honestly, it's the most misunderstood subclass in the Player’s Handbook.
Most players think choosing a Great Old One (GOO) patron means they have to act like a Cthulhu cultist. That’s one way to do it, sure. But the actual mechanics and the lore written in books like Mordenkainen Presents: Monsters of the Multiverse or the classic Player’s Handbook suggest something much more nuanced. You aren't necessarily a servant. Sometimes, you’re just a parasite. You’ve stumbled upon a fragment of forbidden knowledge, and now your brain is leaking magic. It’s messy, it’s creepy, and if you play it right, it’s the most flavor-rich experience in Fifth Edition.
Who Are These Things?
The multiverse is big. Way bigger than the Nine Hells or the Abyss. Outside the neat little bubble of the planes sits the Far Realm. This is where DnD Great Old One patrons hang out. They are entities of madness.
Think about Hadar. In Xanathar’s Guide to Everything, we see spells named after him, like Arms of Hadar or Hunger of Hadar. He’s often described as a "Dark Hunger," a dying star that wants to consume everything. Then you’ve got Caiphon, a purple star that offers guidance to travelers but usually leads them into the mouths of monsters. These aren't just "evil guys." They are fundamental breaks in reality. They don't want your soul for a collection; they might just want to use your eyes to see a dimension they can't normally reach.
Other big names include Ghaunadaur, the god of slimes and everything crusty and gross. Or Tharizdun, the Chained God, who is basically the reason the Abyss exists in the first place. Some players even go for Dendar the Night Serpent, who eats the nightmares of the world. If Dendar eats all the nightmares, the world ends. So, technically, by being a Warlock for Dendar, you’re helping the world sleep better? Sorta. Until the apocalypse happens.
The Telepathy Problem
The level 1 feature, Awakened Mind, is basically the GOO Warlock's bread and butter. You can speak telepathically to any creature you can see within 30 feet.
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Here is what people get wrong: the RAW (Rules as Written) doesn't say they can talk back. It’s a one-way street. You’re broadcasting your thoughts into their skull. This is incredibly powerful for roleplay. You can threaten a guard without the rest of the party hearing. You can coordinate a plan while tied up and gagged. You can literally just whisper "I know what you did" into a noble's mind and watch them freak out.
But it’s also a curse. Imagine the flavor. Does your voice sound like your own? Or is it a chorus of wet, clicking sounds? Does the person you’re talking to get a nosebleed? If you want to make your DnD Great Old One patrons feel real, you have to describe the cost of that telepathy. It shouldn't be clean. It should be intrusive.
Playing the "Accidental" Warlock
Not every Warlock signed a contract in blood. For a Great Old One pact, the "deal" is often a total accident.
Maybe your character found a book bound in something that wasn't leather. Maybe you looked through a telescope at the wrong time and saw a moon blink. Suddenly, you have powers. You didn't ask for them. Your patron doesn't even know your name. You are basically a mosquito that landed on a nuclear reactor and started glowing.
This creates a dynamic where the Warlock is terrified of their own power. Unlike a Fiend Warlock who might be looking for a way out of a contract, a GOO Warlock is looking for a way to turn off the noise in their head. It changes the "Warlock/Patron" relationship from a business transaction to a survival horror story. You’re using the magic of the Far Realm to defend yourself, but every time you cast Eldritch Blast, you feel a little more of your sanity fraying at the edges.
Mechanics That Actually Matter
Let's talk about Entropic Ward at level 6. It’s a defensive move. When a creature attacks you, you can use your reaction to impose disadvantage. If they miss, your next attack against them has advantage.
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- It’s a "No, you" button.
- It scales perfectly because it’s based on the enemy's attack, not your stats.
- It represents you literally warping fate around you.
Then there’s Thought Shield at level 10. You get resistance to psychic damage. More importantly, if someone tries to read your mind, they take psychic damage. Your brain becomes a "do not enter" zone. This is huge in high-level campaigns where Mind Flayers or Aboleths are common. You aren't just a caster; you are a psychic fortress.
And finally, Create Thrall at level 14. You touch an incapacitated humanoid and they are permanently charmed by you. No save every hour. No "until you take damage." They are just yours. It’s dark. It’s ethically questionable. It’s exactly why people play this subclass. You aren't the hero in shining armor; you're the person who rewires people's brains because your patron doesn't understand the concept of free will.
Reality Check: The Limitations
Is the Great Old One the strongest Warlock? Honestly, probably not.
The Hexblade usually takes the crown for raw damage. The Genie Warlock is better for utility and has that cool lamp. The GOO Warlock is a bit of a "middle of the road" pick if you’re just looking at the numbers. Their spell list is heavy on control—things like Tasha’s Hideous Laughter, Phantasmal Force, and Evard’s Black Tentacles. You aren't a nuker. You are a puppeteer.
If your DM runs a "kick in the door" style dungeon crawl with no social interaction, you’re going to feel underpowered. Your best features—telepathy, mind reading, and charming—happen in the roleplay pillar of the game. If you’re playing a GOO Warlock, you need to talk to your DM and make sure there will be NPCs to manipulate. Otherwise, you’re just a worse version of a Wizard.
Making Your Patron Feel Real
Don't let your patron just be a name on a character sheet.
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Give them a quirk. Maybe whenever you use a spell slot, the temperature in the room drops five degrees. Maybe your shadows move a second later than you do. If your patron is Zargon, the Returner, maybe you always smell slightly like rot no matter how much you bathe. These details are what make DnD Great Old One patrons memorable.
You should also decide how "aware" the patron is.
- The Sleeping God: The patron is asleep. Your magic is just their "snoring" leaking into reality. If they wake up, you—and probably the world—are toast.
- The Curious Scientist: The patron is watching you like a bug in a jar. They give you power just to see what a mortal does with it.
- The Incomprehensible Force: There is no "will." It’s just a rift in space. You are drawing power from it like a solar panel draws from the sun.
Actionable Steps for Your Next Session
If you’re ready to dive into the madness, don't just pick "Cthulhu" and call it a day. Start by choosing a specific flavor of cosmic horror.
First, look at the expanded spell list and pick one "signature" spell that you flavor as your patron's direct influence. If it's Dissonant Whispers, describe exactly what the target hears. Is it the sound of a thousand grinding teeth? Is it the voice of their dead mother telling them they forgot to lock the door? Be specific.
Second, utilize Eldritch Invocations that lean into the theme. Gaze of Two Minds is creepy and perfect for a GOO Warlock. Misty Visions lets you create silent images—perfect for manifesting the strange geometries of the Far Realm.
Finally, talk to your DM about Sanity checks. If you want to go hardcore, use the optional Sanity score rules from the Dungeon Master’s Guide. It adds a layer of risk to your power. Every time you commune with your patron, you risk a temporary madness. It makes every level-up feel like a dangerous gamble.
The Great Old One isn't about winning the fight; it's about changing the rules of the world until the fight doesn't matter anymore. Stop trying to be a "good" Warlock and start being an interesting one.