D&D 5E Mythological Figures: Cú Chulainn

Prepare yourself for an epic post in Mythological Figures today because we’re going after an epic guy with a story as gripping and intriguing as any character posted yet: Cú Chulainn!

Cú Chulainn banner DnD 5e.jpg

Seriously everybody you need to strap in for this. Get your coffee, walk the dog, do whatever is you have to do because if you don't know who this guy is yet, you are going to be hard pressed to take a break in here. It's a wild and rambling journey so consider yourselves warned.

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Cú Chulainn (formerly Sétanta and also known as Cú Chulaind, Cúchulainn, or Cuhullin) was almost the great grandson of Balor (by way of his would-be father Lug), but when it is revealed that she carried child the betrothed Deichtine aborts the demigod in her womb and bears her husband Sualtam mac Róich’s son, naming it as the warrior god told her: Sétanta. Or maybe they find Lug in a house where Deichtine is giving birth to Sétanta who is definitely his son. It’s not completely clear. After that it becomes a bit of a “5 Men, Findchóem, and a Baby” scenario among the nobles of Ulster. A fellow named Morann (who I can’t quite dig up much on, although it seems he was known for judging and as “the Arbiter”) tells them that they will raise Sétanta together: Kingly Conchobar, Sencha mac Ailella for judgement and eloquence, Blaí Briugu to be the rich one, Fergus mac Róich to train him in combat, Amergin the poet to teach him, and then Amergin’s wife Findchóem to nurse him alongside their own son (Conall Cernach).

There are three big legends about this hero in his childhood: his first ríastrad (warp spasm aka berserk rage), how he got his final name, and taking up arms as a 7 year old to kill a trio of grown men. The initial rage happens when Sétanta tries to join the boy-troop at Emain Macha where he breaks the rules by not asking for their protection before entering the game’s boundaries, freaks out and beats them all, and then afterwards chases after them demanding they ask for his protection. In the next tale his hurling skills so impress the King of Ulster (Conchobar mac Nessa) that he is invited to a feast at the house of the smith Culann. Although he agrees Sétanta wants to finish his game first and then the king forgets to tell anyone else about the invitation, so the smith’s fearsome hound is let loose to protect the grounds during the meal—a fight ensues and the boy kills the enormous dog. In recompense Sétanta offers to do the tasks of Culann’s guard dog until it can be replaced, earning him the new name of Cú Chulainn (Culann’s hound). Finally there’s the day he takes up arms. Cú Chulainn asks Cathbad why he’s teaching students that the day is auspicious and darts away after being told that, “any warrior who takes arms today will have everlasting fame,” gone before he can hear the other part of the prophecy (“but their life would be short”). Despite his age the boy demands weapons from Conchobar, but none satisfy aside from the older warrior’s own armaments, and then a chariot of which only the king’s is fitting. Eager Cú Chulainn rushes off and slays three sons of Nechtan Scéne (for the claim they’d kill more men of Ulster than those who still lived) and is still in a ríastrad upon returning so Mugain (the wife of Conchobar) has the women of Emain flash him, he’s dunked into three barrels of cold water by the men of Ulster, and though the first explodes and the second boils, the last does the trick.

Then Cú Chulainn gets trained by a scotswoman. See he’s a real looker and the men of Ulster are worried he’ll take their wives or seduce their daughters, but the only woman Cú Chulainn wants is Emer, the daughter of Forgall Monach. Unfortunately he is refused by the supposed King of the Gauls (how Forgall disguised himself) because Forgall’s older daughter is unwed, and so is told to train with Scáthach in Alba (what is now Scotland) with the idea that it will be too much and lead to Cú Chulainn’s death. What’s getting this bit a whole paragraph is that she lives in Dún Scáith also known as the FORTRESS of SHADOWS. From Scáthach he learns how to use the barbed spear (gáe bulg) alongside Ferdiad, a man he gets very close to. Maybe even romantic with! He definitely gets with his teacher’s sister Aífe after Scáthach tries to keep him out of the conflict betwixt them by using a sleeping potion—only for it to last just an hour and him to come charging in. Cú Chulainn and Aífe are evenly matched until he pulls a dirty trick, yelling that her treasured horse and chariot have fallen off a cliff, at which point he grabs her and holds her at swordpoint until she agrees to end the feud and be the mother of his son. Despite succeeding at the task given to him, Cú Chulainn’s proposal to Emer is refused again by Forgall so he storms in, kills two dozen warriors (as well as the old man, who dies from a long fall), and takes her away alongside some loot. Although the King of Ulster has the right to be the first to sleep with the new bride he is (rightfully) fearful of her husband, so at Cathbad’s suggestion the teacher sleeps between her and the king that night.

Less than a decade later Cú Chulainn's son Connla (from Aífe) arrives unannounced, refuses to declare who he is (raised not to identify himself or refuse challenges), and is summarily killed in a planned act of revenge against his father by his mother (for having another woman after her). It’s a close fight though and Connla only fails because he discovers that he’s about to kill his father, whispering a revelation with his last words that he would’ve “carried the flag of Ulster to the gates of Rome and beyond”. Understandably, Cú Chulainn is wracked with grief by the ordeal.

There’s more about this legendary hero but this is getting long-winded so let’s try to summarize a few other exploits:
  • While away from Ireland Cú Chulainn saves a Scandinavian princess he later nearly kills when she’s transformed as a swan, then gives her to a foster-son who becomes High King of Ireland except the Stone of Destiny cries out as it judges the new monarch so he splits it in two.
  • He single-handed defeats the army of Connacht in the epic Táin Bó Cúailnge when queen Medb tries to take the stud bull of Donn Cúailnge (aka The Cattle Raid of Cooley or The Táin). Cú Chulainn fails to catch them at the border because he was getting busy with a lady, and a curse disables the Ulstermen making them suffer like they were giving birth. By invoking the right of single combat repeatedly he kills and kills and kills enemies one by one until a gorgeous woman claiming to be a princess interrupts the fray offering her love only to be refused—a bad mistake as she’s the Morrígan, a goddess of battle, and she doesn’t much like being turned down. While fighting the warrior Lóch (a man who initially refuses to fight a tender young beardless lad) she attacks Cú Chulainn as an eel, a wolf, and a cow but he continues on victoriously. When he’s starting to succumb to his injuries Lug appears and heals his wounds, only for him to wake up and see the boy-troop of Emain (his buddies from childhood) die by the blades of the Connacht (the first of many callbacks here). Cú Chulainn goes into his baddest rage yet becoming monstrous in his anger (physically so if the epic is to be believed) and kills hundreds of warriors to build himself a corpse wall. Currently exiled and in the court of Medb, one of his foster-fathers Fergus mac Róich (the one who trained Cú Chulainn in combat) gets Cú Chulainn to agree not to fight him so long as when they next meet Fergus will back down. Then there’s a three day duel against Ferdiad (another callback!) before the men of Ulster finally get into the battle themselves giving Cú Chulainn a break—until Fergus shows up, upholds the agreement, and pulls his soldiers away causing the army of Connacht to break. Although he certainly has the chance to kill Medb Cú Chulainn chooses not to, thinking it wrong to kill a woman, so he covers her retreat for a ways instead.
  • The mischievous poet and healer Bricriu convinces Cú Chulainn, Conall Cernach, and Lóegaire Búadach to take part in a contest to be honored as the champion at a feast, and although Cú Chulainn is clearly the winner his competitors refuse to accept it. Cú Roí (the son of Dáire of Munster) appears to each as a peasant demanding to be beheaded with the understanding that he’ll return to do the same. Only Cú Chulainn has the requisite courage and honor to be true to his word, and so he is spared and declared the winner. Later on this fellow appears again, infiltrating the men of Ulster to take part in a raid on probably the Isle of Man where he forcibly takes the princess Blathnát as his share. She figures out the trick to killing Cú Roí, gets Cú Chulainn to do it, and then dies when the poet Ferchertne takes revenge by way of a murder-suicide.
  • There’s a story where Emer gets jealous over Fand, a fairy and the abandoned wife of Manannán mac Lir. When she is assailed by three Fomorians asserting authority over the Irish Sea, Cú Chulainn agrees to defend her in exchange for marrying him. Envious Emer tries to kill the fairy but upon seeing the depth of her love for Cú Chulainn stays her hand, deciding to give him up instead. Fand is so moved that she relinquishes him (his presence would’ve meant doom for the faeries anyway) and returns to Manannan. The King of the Underworld shakes his cloak between Cú Chulainn and Fand, cursing them to never again meet, then afterward the berserker and Emer drink potions that wipe their memories of the whole affair.
In 1 AD Medb conspires with Lugaid (the son of Cú Roí) and other men who’ve had fathers killed by Cú Chulainn to see him killed. To do so she first tricks him into eating dog meat by having an old woman offer him a meal with it (leaving him no choice but to accept), weakening his spirit, and then Lugaid has three king-killing spears forged—the first is used against Láeg the King of Chariot Drivers, the second against Cú Chulainn’s mount Liath Macha the King of Steeds, and the last delivering a mortal wound upon the warrior legend himself. Cú Chulainn won’t die on his feet so he ties himself against the standing stone Clochafarmore, fighting so long and hard that his enemies only believe him dead when a raven sits upon his shoulder. Finally victorious, Lugaid goes to decapitate the corpse but something called the “hero-light” flares around Cú Chulainn and cuts off his hand! The aura continues until the dead body’s right hand and sword arm are removed. However his stepbrother Conall Cernach swore to avenge Cú Chulainn should he die and sets off to kill Lugaid before the sun sets that day. Fighting one-handed to keep things even, Conall has his vengeance when his horse distracts his opponent with a nasty bite.

Design Notes: Jeeze. God bless those of you still with us. What an epic guy! To be as fearsome a warrior as Cú Chulainn is there was no question about a split between fighter and barbarian levels, but there was some consideration for how to do that split. While Intimidating Presence certainly felt apropos, this build instead is going for more fighter levels to get that extra Extra Attack and to have that +1d6 to keep popping back up after getting dropped to 0 hit points. This whole thing is wordy enough though isn’t it? Let’s do the numbers! The DMG rubric boils out to 14.75 and the Blog of Holding 14.8, and though that’s a beefy 14 it’s pretty airtight so Cú Chulainn’s final CR is going to land there.

Cú Chulainn

Medium humanoid (human), lawful neutral barbarian (berserker) 9/fighter (brute) 11
Armor Class 19 (Constitution, shield)
Hit Points 199 (9d12+11d10+80)
Speed 40 ft.

18 (+4)​
16 (+3)​
18 (+4)​
10 (+0)​
9 (–1)​
14 (+2)​

Saving Throws Str +10, Con +10
Skills Animal Handling +5, Athletics +10, Intimidation +7, Survival +5; vehicles (land) +9
Senses passive Perception 9
Languages Gaelic
Challenge 14 (11,500 XP)

Background: Folk Hero. Cú Chulainn is always able to rely on the hospitality of commoners to help him hide or rest provided he poses no danger in doing so, going so far as to shield him from being discovered (though not at the cost of their lives).

Action Surge (1/Short Rest). Once on his turn, Cú Chulainn can take an additional action on top of his regular action and a possible bonus action.

Brutal Critical. Cú Chulainn can roll one additional weapon damage die when determining the extra damage for a critical hit with a melee attack.

Brutal Toughness. Cú Chulainn gains a +1d6 bonus to saving throws and death saves (treating final results of 20 or higher on a death saving throw as a natural 20).

Danger Sense. Cú Chulainn has advantage on Dexterity saving throws against effects that he can see, such as traps and spells. To gain this benefit, he can’t be blinded, deafened, or incapacitated.

Feat: Athletic. Cú Chulainn can stand up from being prone with only 5 feet of his movement, climbing doesn’t cost him extra movement, and he only has to move 5 feet before making a running long jump or running high jump.

Feat: Master of the Spear. Cú Chulainn can increase his reach with a spear by 5 feet until the end of his turn by using a bonus action. In addition, he can prepare his spear to resist a charge by using a bonus action. Cú Chulainn chooses a creature within 20 feet that he can see and if on his next turn it moves within his reach, Cú Chulainn can use his reaction to make a melee attack against it using his spear. On a hit he deals an extra damage die. A creature that used Disengage does not provoke an attack from Cú Chulainn.

Feral Instinct. Cú Chulainn has advantage on initiative rolls. Additionally, if he is surprised at the beginning of combat and isn’t incapacitated, he can act normally on his first turn, but only if he enters his rage before doing anything else on that turn.

Indomitable (1/Long Rest). Cú Chulainn can reroll a saving throw that he fails but must use the new roll.

Mindless Rage. Cú Chulainn can’t be charmed or frightened while raging. If he is charmed or frightened when he enters his rage, the effect is suspended for the duration of the rage.

Rage (4/Long Rest). On his turn, Cú Chulainn can enter a rage as a bonus action. His rage lasts until Cú Chulainn is knocked unconscious. Cú Chulainn can also end his rage on his turn as a bonus action. Cú Chulainn can go into a frenzy when he rages. If he does so, for the duration of his rage he can make a single melee weapon attack as a bonus action on each of his turns after his first turn raging. When his frenzied rage ends, he suffers one level of exhaustion. While raging, he gains the following benefits:
  • advantage on Strength checks and Strength saving throws,
  • when he makes a melee weapon attack using Strength he gains a +3 bonus to the damage roll,
  • and he has resistance to bludgeoning, piercing, and slashing damage.
Reckless Attack. When Cú Chulainn makes his first attack on his turn, he can decide to attack recklessly. Doing so gives him advantage on melee weapon attack rolls using Strength during this turn, but attack rolls against him have advantage until his next turn.

Second Wind (1/Short Rest). On his turn, Cú Chulainn can use a bonus action to regain 1d10+11 hit points.


Extra Attack. Cú Chulainn attacks three times when he takes the Attack action (and can use a bonus action to attack a fourth time if both raging and frenzied).

Spear. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 14 (1d8+1d6+6) piercing damage.

Spear. Ranged Weapon Attack: +11 to hit, range 20/60 ft., one target. Hit: 12 (1d8+1d6+4) piercing damage.
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Mike Myler

Mike Myler


Scion of Murgen (He/Him)
The legend! A good short summary!

One detail I might have included is that he had a Geas (taboo/prohibition) against eating dog flesh, which is why he was weakened by it. A recurring theme in the great heroic Irish tales is a hero being put in the no-way-out position with two conflicting oaths or geasa, which almost always leads to a tragic end.


Laws of Mordenkainen, Elminster, & Fistandantilus
Whoa...how come I never thought of Cú Chulainn for a write-up? Now it seems such an obvious pick. Great job, Mike!

Mike Myler

Have you been to LevelUp5E.com yet?
The legend! A good short summary!

One detail I might have included is that he had a Geas (taboo/prohibition) against eating dog flesh, which is why he was weakened by it. A recurring theme in the great heroic Irish tales is a hero being put in the no-way-out position with two conflicting oaths or geasa, which almost always leads to a tragic end.
Yes what this write-up was missing is more details :3


It has been claimed that he had seven fingers on each hand, seven toes on each foot, and seven pupils in each eye.

I prefer to think of that as evidence that the Tain's author was using some really, really bad drugs when this thing got written down.


It has been claimed that he had seven fingers on each hand, seven toes on each foot, and seven pupils in each eye.

I prefer to think of that as evidence that the Tain's author was using some really, really bad drugs when this thing got written down.
Great write up from MM here. Love that fact it uses my favorite UA fighter archetype the Brute

Seven pupils is obviously mystical and seven pupils would not happen in nature at least in a surviving fetus.

Seven fingers and toes is plausible though as people have been proven to have been born with up to twelve fingers and toes!

Aaron L

Great stuff!
Celtic mythology can be pretty crazy; for example, the descriptions of the Warp Spasm sound nightmarish. I used Celtic mythology to name my current main PC, a 9th level Half-Elven Bard of the College of Swords named Taliesin, and his father Gwydion (two legendary Celtic Bards.)

And Taliesin is absolutely the most badass character in our party,

In our last game session this past Sunday I turned a major combat engagement that our DM thought might kill one of us (a Night Hag, two Bone Devils, and a VERY HIGH LEVEL Warlock) into a cakewalk with a single stealthily cast Hypnotic Pattern that got all of them (DC 17 Wisdom save with Disadvantage due to his Doss Lute, which he rocks out on like a guitar) and a subsequent Charm Monster on a Bone Devil. I then waded into combat with three attacks per round (wielding twin rapiers) and an Armor Class that could hit 31 in short bursts due to my Defensive Flourish, while every so often pausing to heal the other party members (I am also the party's primary healer and we do just fine.)

And if one of us had died, I could have Raised them.

If anyone ever tells you that Bards are weak or lame, you laugh at them.
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