The artifact is mentioned in: Baba Yaga's Hut - DMG1 156
"Baba Yaga’s Hut: Ages ago the most powerful female mage ever known spent much of her power in the creation of a magical dwelling of superb character. When she passed to another plane, her hut disappeared and has only been rumored to have been seen once or twice since. Baba Yaga developed a small hut of ordinary appearance - a circular, thatched structure of 15’ diameter and 10’ high. To this dwelling are attached two powerful fowl legs 12’ long, which appear to be stilts. Furthermore, the Hut has intelligence (high) and human senses, plus infravision to 120’ and ultravision. Inside, the Hut is a small palace - garden, fountains of water and wine, and 30 rooms on 3 floors, all lavishly and richly furnished! Despite the commodious interior, the bird legs can move Baba Yaga‘s Hut at up to 48’ speed over swamp, 36’ over rough or normal terrain, 12” over hills, through forests, etc. The Hut will obey commands from 1 person (the one first using a key phrase) and can come to a call from as far away as 1 league. Its legs deliver blows equal to those of a hill giant, 2 attacks per round, to any so rash as to come near without invitation or knowing the command phrase. The legs are armor class 2 and can take 48 hit points damage each, regenerating at 1 hit point/melee round. The walls of the Hut are the equivalent of 5’ thick granite. The Hut has the following additional powers/effects:
4 x I:
2 x (I:
1 x 111:
1 x IV:
1 xv:
1 x VI:"
The Hut is also mentioned in Dragon83 32,
"The Hut's appearance
Baba Yaga spent much of her early life constructing the Dancing Hut, which now serves as her mobile fortress, home, and helper. The Dancing Hut is a small, windowless log cabin, hexagonal in shape, with a decorated wooden roof. Only 15' wide and 12' high at the peak of the roof, with a small chimney on top, the Hut does not appear very impressive--except for the 12' long chicken legs coming out from the bottom.
When first sighted, the Hut will usually be "dancing" by spinning about rapidly on its feet. The Hut will make about one revolution every six or seven seconds, with the feet stamping the ground every half second. If someone is entering or leaving the Hut, the legs will fold up into a 2-foot-deep crawlspace beneath it, so that the Hut rests on the ground. If so commanded by Baba Yaga, the two huge legs can move the Hut at a very rapid pace (48" over smooth ground, 36" over rough terrain or swampland, 24" through woods and mountains). About 2' thick, the legs are treated as AC -2 and may only be struck by magical weapons. Each leg has 45 HP, and if damaged by weapon blows will regenerate 3 HP per round. As noted below, the legs are immune to all magic.
When attacking (if commanded to do so, if attacked, or under other conditions described below), the legs strike as 10 HD monsters, once each per round, for 4-24 HP damage. If a leg catches a victim with a score of 4 or more over the roll needed to hit, the victim's arms are pinned by the claws, and the attacker may be crushed to the ground for 4-40 HP damage (40% chance), or hurled 20-120 feet away for 1d6 damage per 10' thrown (60% chance). Thrown characters must make a saving throw vs. paralysis or be stunned upon
impact for 2-12 rounds, unable to move, attack, or defend themselves. Crushed characters will be hurled away in the following melee round.
No matter whether the Hut is spinning, fighting, or running, the interior will remain stable and calm, because of its extraplanar construction. Other powers of the Hut may be used under Baba Yaga's direction, and they are described in area 46 below.
The Hut itself is powerfully enchanted. Close examination will show fine magical runes covering every square inch of its outer surface. The Hut's exterior (including the legs) is not affected by any magical spell, and it will reflect spells cast directly upon it (such as fireball, lightning bolt, or magic missile), inflicting them on the caster. Area effect spells not centered on the Hut will not be reflected back, but they will not affect the Hut, either. Though the walls are made of wood, the Hut is immune to all forms of fire, acid, cold, water, and lightning. Physical attacks have no effect upon the cabin section of the Hut.
No form of divinatory spell, not even a wish, will reveal the Hut's current location (its protection resembles that offered by an amulet of proof against detection and location).
"You'll find it when you see it," say the sages."
The Hut is also mentioned in BoA 21, The Dancing Hut of Baba Yaga adventure
Also try Baba Yaga:The First Setting in Rassiya. It was written by Michael Fiegel and published by the good folks at Dog Soul. It also won a gold ENnie in 2006. I hear it is an excellent supplement and certainly deserved the award.
The best d20/v.3.5/OGL I could find was SHADE's information on EnWorld but unfortunately it is only started and unfortunately incomplete (not sure its edited right, and certainly not playtested)... the final version is saved to a file of homebrews that I can't seem to access right now, but I can try again later. Here is what I can copy over for you for now:
Baba Yaga's Hut
Huge N Construct CR 25
Hit Dice: 40d10+40 (260 hp)
Initiative: +x
Speed: 120 ft. (24 squares)
AC: 22+ (–2 size, +x Dex, +x natural), touch x, flat-footed x
(The legs are really tough, DR 15/adamantine and epic; +20 natural armor)
Climb, Jump, Move Silently, Swim?
Base Attack/Grapple: +30/+x
Attack: Claw +x melee (4d6+x)
Full Attack: 2 claws +x melee (4d6+x)
Space/Reach: 15 ft./15 ft.
Special Attacks: Crush/pin, improved grab
Special Qualities: Construct traits, damage reduction x/adamantine and epic;
Feats: (14 total, 7 can be epic); Combat Expertise, Dodge, Epic Fortitude, Epic Reflexes, Epic Skill Focus (Jump), Epic Skill Focus (Swim), Epic Will, Improved Critical (claw), Legendary Leaper, Mobility, Power Attack, Run, Spring Attack, Whirlwind Attack
All-around vision due to its constant spinning?
__________________
damage reduction x/adamantine and epic, darkvision 60 ft., immunity to acid, cold, electricity, and fire, immunity to magic, "immunity to water", "immunity to divinations", low-light vision, reflective exterior
Saves: Fort +14, Ref +12, Will +14
ABilities: Str 40, Dex 14, Con —, Int 14, Wis 11, Cha 11
Skills: - Skills: 4 at 44 ranks
Feats: Improved Grab, hurl, Smash
Environment: x
Organization: Solitary or with Baba Yaga
Challenge Rating: x
Treasure: x
Alignment: Neutral?
Advancement: -
Level Adjustment: -
Immunity to Magic (Ex): Baba Yaga's Hut is immune to any spell or spell-like ability that allows spell resistance.
Reflective Exterior (Ex): The Hut's walls are powerfully enchanted, deflecting all rays, lines, cones, and even magic missile spells. There is a 30% chance of reflecting any such effect back at the caster; otherwise, it is merely negated.
Improved Grab (Ex): To use this ability, the Hut must hit a Large or smaller opponent with a claw attack. It can then attempt to start a grapple as a free action without provoking an attack of opportunity. If it wins the grapple check, it establishes a hold and can try to smash or hurl the opponent.
Hurl (Ex): The Hut can hurl a grappled creature as a standard action. A hurled creature travels 2d6 x 10 feet, and takes 1d6 points of damage per 10 feet traveled. The victim must also succeed on a DC X Fortitude save or be stunned for 2d6 rounds. The save DC is Strength-based.
Smash (Ex): The Hut may attempt to smash a grappled creature to the ground as a free action. With a successful grapple check, the victim takes 4d10+(Str and 1/2?) bludgeoning damage and is considred pinned. The Hut usually hurls a smashed opponent in the following round.
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Depending on the age of the Folklore Baba Yaga changes from being the Mother of the Thunder god, to a Powerful Storm Spirit, to a fey Hag, to an old Witch. You might cast her as a Outsider (so Night Hag with Class levels perhaps? or unique native outsider, but akin to night hags).
It might have been Dragon 344(?) where Baba Yaga is mentioned helpping Kostchtchie get his start. (Thank James & Erik for that.)
Using the "divide old edition hit points by 4.5" method, she'd have 30 Hit Dice. Comparing her 1e hit points to other unique outsider's 1E hit points, she's about on par with Geryon, who has...30 Hit Dice in 3E. So, getting started...
Baba Yaga
Medium Outsider (Evil, Native)
Hit Dice: 30d8+240 (375 hp)
Initiative: +11
Speed: 30 ft. (6 squares)
Armor Class: 42 (+7 Dex, +7 natural, +10 deflection, +8 insight), touch 35, flat-footed 35
Base Attack/Grapple: +30/+39
Attack: Claw +39 melee (1d8+9/19-20)
Full Attack: 2 claws +39 melee (1d8+9/19-20) and bite +34 melee (2d6+4)
Space/Reach: 5 ft./5 ft.
Special Attacks: Aura of horror, consume spirits, deadly rending, spell-like abilities, spells
Special Qualities: Change shape, damage reduction 15/magic (15/magic and non-metal within her hut), darkvision 120 ft., immunity to mind-affecting spells and abilities, magical aging effects, and necromantic effects, knowledgeable, resistance to cold 10 and fire 10, regeneration 3, scent, "sniff out knowledge", spell resistance 41, tongues
Saves: Fort +25, Ref +24, Will +27
Abilities: Str 29, Dex 24, Con 26, Int 32, Wis 30, Cha 27
Skills: Bluff +41, Concentration +41, Decipher Script +44, Diplomacy +45, Disguise +41 (+43 acting), Hide +40, Intimidate +43, Knowledge (arcana) +44, Knowledge (local) +44, Knowledge (nature) +46, Knowledge (the planes) +44, Listen +43, Move Silently +40, Search +44, Sense Motive +43, Spellcraft +46 (+48 scrolls), Spot +43, Survival +43 (+45 following tracks, +45 on other planes), Use Magic Device +41 (+45 scrolls)
Feats: Brew Potion (B), Empower Spell, Extend Spell, Heighten Spell, Improved Critical (claw), Improved Initiative (B), Improved Metamagic, Improved Spell Capacity (x2), Intensify Spell, Maximize Spell, Power Attack, Quicken Spell
Environment: Temperate and cold forest
Organization: Solitary
Challenge Rating: 25
Treasure: Double standard
Alignment: Always neutral evil
Advancement: -
Level Adjustment: -
Baba Yaga stands 5 feet tall and weighs 100 pounds.
Baba Yaga speaks Abyssal, Common, Draconic, Infernal, and Sylvan, but can speak with almost any creature because of her tongues ability.
Combat
Aura of Horror (Su): Baba Yaga can radiate a 15-foot-radius fear aura as a free action. A creature in the area must succeed on a DC 33 Will save or be affected as though by a fear spell (caster level 20th). A creature that successfully saves cannot be affected again by Baba Yaga's aura for 24 hours. The save DC is Charisma-based.
Change Shape (Su): Baba Yaga can assume the form of any Small, Medium, or Large animal or humanoid.
Consume Spirits (Su): When Baba Yaga slays a humanoid opponent, she can devour its life force, as a full-round action. This prevents any form of raising or resurrection that requires part of the corpse. There is a 50% chance that a wish, miracle, or true resurrection spell can restore a consumed victim to life. Check once for each destroyed creature. If the check fails, the creature cannot be brought back to life by mortal magic.
Baba Yaga heals 10 hit points per Hit Die of the creature whose spirit she consumes.
Deadly Rending (Ex): If Baba Yaga hits with both claw attacks and her bite attack, she latches onto the opponent’s body and tears the flesh. This attack automatically deals an additional 4d6+13 points of damage. Additionally, the victim must succeed on a DC 34 Fortitude save or die. This is a death effect. The save DC is Strength-based.
Knowledgeable (Ex): Baba Yaga makes Knowledge checks for any Knowledge skills as if she had a minimum of 10 ranks in that skill. To surpass the 10-rank minimum, she must assign more than 10 ranks to the skill as normal.
Regeneration (Ex): Fire and acid deal normal damage to Baba Yaga. If Baba Yaga loses a limb or body part, the lost portion regrows in 3d6 minutes. She can reattach the severed member instantly by holding it to the stump.
Sniff Out Knowledge (Su): If Baba Yaga successfully detects a creature via her scent ability, she gains a +10 circumstance bonus on Knowledge checks made to identify monsters and their special powers or vulnerabilities. She may also discern the creature's nationality if she succeeds on a Knowledge (local) check (DC equals 10 + creature's HD). With a standard action, she may discern a creatures alignment as if using detect chaos/evil/good/law.
Spell-Like Abilities: At will--comprehend languages, detect magic, discern lies (DC 22), read magic. Caster level 20th. The save DCs are Charisma-based.
Spells: Baba Yaga casts spells a 25th level wizard. Baba Yaga can also add spells found on scrolls, or other sources, containing divine spells to her arcane spellbook. Baba Yaga can learn and thus prepare divine spells in this fashion as if they were on the sorcerer/wizard spell list at the same level.
Typical Wizard Spells Prepared (CL 25th, save DC 18 + spell level)
0-- arcane mark, ghost sound, mending, prestidigitation (4 total)
1st-- deathwatch, expeditious retreat, mage armor, pass without trace, shield, unseen servant, ventriloquism (7 total)
2nd-- death knell, desecrate, misdirection, spectral hand, tree shape, undetectable alignment, warp wood (7 total)
3rd-- bestow curse, deeper darkness, diminish plants, dominate animal, haste, maximized ray of enfeeblement, nondetection (7 total)
4th-- blight, extended fly, freedom of movement, giant vermin, quickened true strike, rusting grasp (6 total)
5th-- commune with nature, extended greater invisibility, insect plague, maximized lightning bolt, quickened scorching ray, true seeing (6 total)
6th-- geas, greater dispel magic, liveoak, maximized enervation, quickened bestow curse, word of recall (6 total)
7th-- blasphemy, control weather, creeping doom, empowered quickened vampiric touch, heightened dominate person, plane shift (6 total)
8th-- control plants, greater prying eyes, intensified scorching ray, moment of prescience, unholy aura (5 total)
9th-- foresight, quickened greater dispel magic, shambler, weird, wail of the banshee (5 total)
10th -- heightened bestow curse, quickened greater teleport (2 total)
11th -- empowered maximized horrid wilting, intensified cloudkill (2 total)
Tongues (Su): Baba Yaga can speak with any creature that has a language, as though using a tongues spell (caster level 20th). This ability is always active.
Skills: Baba Yaga has a +4 racial bonus on Listen and Spot checks.