I have this statblock for a Huge sized advanced Bone Lurker, based on the one that the demon made for me from the hydra bones. It doesn't have as much HP as the demon's, but it's as good as Posey could possibly make with her scroll.
Hone Kujira (advanced Bone Lurker)
Huge Undead
Alignment: Neutral Evil
Initiative: +3
AC: 13 (-2 size, -1 Dex, +6 natural), touch 7, flat-footed 14
Hit Dice: 9d12 (68 HP)
Fort +3, Ref +3, Will +6
Speed: 20 ft., fly 30 ft. (poor)
Space: 5 ft. by 15 ft./15 ft.
Base Attack +4; Grapple +22
Attack: slam +12 melee
Damage: Slam 2d6+15
Special Attacks/Actions: Constrict 2d6+15, improved grab, paralysis
Abilities: Str 30, Dex 8, Con -, Int -, Wis 10, Cha 11
Special Qualities: Immunities, undead traits
Feats: Improved Initiative
Skills: -
Constrict (Ex): Hone Kujira deals 2d6+15 points of damage with a successful grapple check.
Improved Grab (Ex): If Hone Kujira hits an opponent that is at least one size category smaller than itself with its slam attack, it deals normal damage and attempts to start a grapple as a free action without provoking an attack of opportunity (grapple bonus +21). Hone Kujira has the option to conduct the grapple normally, or simply use its body to hold the opponent. Either way, each successful grapple check it makes during successive rounds automatically deals slam damage and constrict damage.
Paralysis (Ex): Any creature hit by Hone Kujira's slam attack must succeed at a Fortitude save (DC 14) or be paralyzed for 1d6+2 minutes.
Immunities (Ex): Hone Kujira has cold immunity. Because it lacks flesh or internal organs, it takes only half damage from piercing or slashing weapons.
(This should probably be corrected to DR 5/bludgeoning)
Hone Kujira attacks by dropping onto its prey and wrapping itself around its victim. Dropping down in this fashion is considered a charge attack from higher ground. If Hone Kujira misses its initial attack, it often flies up and tries to drop on the opponent again.
https://www.realmshelps.net/monsters/block/Bone_Lurker%7Calpha%7CAll%7CUndead