Eureeka’s Castle D&D 5E: Batly & Webster

WARNING: Mature Content

I obviously love Eureeka’s Castle. Let’s be plain about that. I really do—it was a formative thing of my youth, I still remember the theme song, and I think it is a wonderful children’s television program. If you have children, or if you are yourself a child, consider queuing up an episode or two instead of reading what’s below. If you are like me however (a jaded adult with a treasure chest of complexes) then by all means continue onward.


The egotistical attitude of the near-sighted Batly came crashing down with the depravity and horrors wrought by Carstigle. His happy demeanor and encouraging curiosity led him into a place of confidence for his friend Magellan, forced to watch as the dragon’s love for Eureeka twisted the scaled creature just as surely as the forbidden arts of blood magic did her heart. Throughout all of the castle it is only he and Mr. Knack who still seek a brighter day, ready to aid anyone that might bring an end to the sanguine dreams of their friend and newest master.

Design Notes: I like me some werebats, I like me some beat-up antiheroes, so you bet your bottoms Batly was the first build I made for the terrible, terrible, terrible things to come here in Eureeka’s Castle D&D 5E. The occultist (which appears in the Book of Exalted Darkness and far more popular Masterclass Codex) was a natural choice for a flying winged bat-person so I went into that full bore. Looking at the numbers, he gets a high CR of 15 out of the DMG chart (likely because of his 21 AC while in hybrid or beast form) while the Blog of Holding rubric comes in at a more reasonable 13.4. The average of 14 (rounded down, naturally) feels like a good fit. I also used the Traitor background from Book of Exalted Darkness as it seemed apropos and gives a mechanical reason for him to have his glasses. tldr Batly here is a 27 ability point score buy pregenerated character! Later on you’ll see Mr. Knack and Eureeka built the same way.



Small humanoid, neutral occultist (werecreature) 16 [B]
Armor Class 18 (natural armor, studded leather; 21 in beast or hybrid form)
Hit Points 120 (16d8+48)
Speed 70 ft., fly 40 ft.; Vilis Points 5


12 (+1) 20 (+5) 16 (+3) 12 (+1) 12 (+1) 14 (+2)​ 8 (–1)

10 (+0)

Saving Throws Str +6, Dex +10, Con +8, Wis +6, Cha +7
Skills Arcana +6, Athletics +6, Deception +7, Insight +6
Damage Resistances piercing, slashing
Damage Immunities bludgeoning, piercing, slashing from weapons that are not silver (while in Lycanthropic Form)
Condition Immunities charmed, frightened, poisoned
Senses darkvision 60 ft. (sees through magical darkness), passive Perception 11
Languages Common
Challenge 14 (11,500 XP)

Background: Traitor – Bribed [B]. Batly gains one magic item of uncommon rarity (eyes of minute seeing). While wearing his glasses, Batly has advantage on Intelligence (Investigation) checks that rely on sight while searching an area or studying an object within 1 foot.

Dark Strike. Batly can use Dexterity or Strength for the attack and damage rolls of his unarmed strikes, and he can roll a d10 in place of the normal damage of his unarmed strike. When he uses the Attack action with an unarmed strike on his turn, he can choose to deal necrotic damage by spending a bonus action. He can use Constitution for the attack and damage rolls of his unarmed strike when dealing necrotic damage.

Devotee of Darkness. Batly has advantage on Dexterity (Stealth) checks and Wisdom (Perception) checks made in darkness or dim light. 

Keen Senses. Batly has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Lycanthropic Form. Batly can use an action to polymorph into a beast-humanoid hybrid or into a bat, or back into his true form. While in hybrid or beast form his AC increases by 3. His statistics, other than his AC, are the same in each form. Any equipment he isn’t wearing or carrying isn’t transformed. Batly reverts to his true form if he dies. When the moon is full he cannot assume human form. Batly can only use his Dark Strike while in hybrid or beast form.

Lycanthropic Hide. While in hybrid or beast form, Batly has immunity to bludgeoning, piercing, and slashing damage from weapons not made with silver.

Powerful Leaps. While in hybrid or beast form, Batly quadruples the distance of any jumps he makes.

Supernatural Save. Batly gains proficiency with Strength, Dexterity, and Wisdom saving throws. He may change which type of saving throw he gains proficiency in by performing an hour long ritual that requires the use of ceremonial relics. At the end of the ritual he makes a DC 14 Charisma check and on a success, he may change one type of saving throw proficiency granted by this feature. On a failed check he cannot change the type of saving throw again for one week. 


Extra Attack. Batly attacks three times when he takes the attack action.
Unarmed. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 10 (1d10+5) bludgeoning damage.

[B] = Book of Exalted Darkness


In order to survive in the twisted and foul stone walls they called home, Batly and Webster became hardened and severe. No longer could the spider remain leashed and when finally given its freedom the arachnid went mad, bounding without restraint and feeding upon any unwary thing that wandered too near Eureeka’s Castle. His bloodlust has saved his master more than once however, and though Batly feels as though he’s done his pet and friend a disservice, he cannot fault the creature’s loyalty or mettle in battle. Should any well-meaning adventurers manage to run afoul of this spider and get on its bad side however, they may well find his master less than helpful—maybe outright murderous.

Design Notes: A raging spider! Yes! I went ahead and cherry-picked my favorite barbarian rage archetype features (super damage resistance, frenzying, that summon an aura business) and otherwise kept the spider basics. If you ever want to really terrify your party, a couple of these screaming and raging in the darkness should do the trick. On the numbers side the DMG chart came out to 5.1667 while the Blog of Holding landed at 6.5 for an average of 5.83333. I’m going to give him a more limited Web ranged attack from the giant spider’s statblock so he can stick somebody then frenzy and round up to 6.


Small beast, chaotic neutral
Armor Class 17
Hit Points 65 (10d6+30)
Speed 40 ft., climb 40 ft.


17 (+3) 25 (+7) 16 (+3) 5 (–3) 10 (+0)

12 (+1)

Saving Throws Con +5, Wis +3
Skills Athletics +6, Stealth +10
Senses blindsight 5 ft., darkvision 60 ft., passive Perception 10
Languages understands Common but can’t speak
Challenge 6 (2,300 XP)

Rage (2/Long Rest). On his turn, Webster can enter a rage as a bonus action. His rage lasts for 1 minute, ending early if he is knocked unconscious or if his turn ends and he hasn’t either attacked a hostile creature since his last turn or taken damage since then. Webster can also end his rage on his turn as a bonus action. While raging, he gains the following benefits: 

  • Webster has advantage on Strength checks and Strength saving throws.
  • When Webster makes a melee weapon attack using Strength, he deals 2 extra damage.
  • Webster has resistance to all damage except for psychic.
  • Webster can use a bonus action while raging to spread the vaporous chaos of murder itself in a 10-foot radius. Total cover blocks this miasma. He chooses a creature in the area when he activates this feature, forcing it to make a DC 14 Constitution saving throw or take 4 (1d8) necrotic damage (success halves).
  • Webster can go into a frenzy when he rages, and can make a single melee weapon attack as a bonus action on each of his turns after he activates his rage. When his rage ends, Webster suffers one level of exhaustion.

Spider Climb. Webster can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Web Sense. While in contact with a web, Webster knows the exact location of any other creature in contact with the same web.

Web Walker. Webster ignores movement restrictions caused by webbing.


Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one creature. Hit: 5 (1d4+3) piercing damage, and the target must succeed on a DC 14 Constitution saving throw or take 5 (2d4) poison damage.
Web (Recharge 6). Ranged Weapon Attack: +10 to hit, range 20/40 ft., one creature. Hit: The target is restrained by webbing. As an action, the restrained target can make a DC 14 Strength check, bursting the webbing on a success. The webbing can also be attacked and destroyed (AC 10; hp 5; vulnerability to fire damage; immunity to bludgeoning, poison, and psychic damage).

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