(5e)Homebrewing Heartless Hidetsugu(Kamigawa)

[HoboKnight]

Hey guys,

so I have a plan for my party, when it will be roaming Kamigawa-ish parts of the Feywild, to meet a character, shaped after the great Ogre-Mage(pre-ascension).

I was thinking of CR15-ish monster, perhaps I could start with Oni. I do not want to make this too complicated to build, a refluffed monster of proper CR would also be great.

I'd appreciate any advice on what monster to take, switch out a few abilities, that reflect Hidetsugus enormous melee abilities, as well as his ability to consume spirits.

Thanks

[HoboKnight]

Not the best at homebrewing, but here is what I came up with:

Mujo Hidetsugu
Large Demon Giant, chaotic evil
AC 10 (18 plate)
Hit Points 180 (19d8 + 95)
Speed 30 ft.
STR: 20(+5) DEX: 11(+0) CON: 20(+5) INT: 12(+1) WIS: 16(+3) CHA: 18(+4)

Saving Throws: Dexterity +6, Wisdom +7, Charisma +10
Damage Immunities: fire, cold, lightning, poison; bludgeoning, piercing, and slashing from nonmagical attacks

Condition Immunities: Frightened, Poisoned
Senses: Darkvision 120 ft., Passive Perception 13
Languages: Sylvan
Challenge Rating: 17 (18,000 XP)

Magic Resistance. The Mujo Hidetsugu has advantage on saving throws against spells and other magical effects.
Spellcasting. The Mujo Hidetsugu is a 19th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 18, +10 to hit with spell attacks). It has the following sorcerer spells prepared:
1st level (4 slots): Expeditious Retreat, Fog Cloud, Shield
2nd level (3 slots): Misty Step, See Invisibility
3rd level (3 slots): Slow, Fear
4th level (3 slots): Confusion, Dimension Door
5th level (2 slots): Cone of Cold

Actions
Multiattack. The Mujo Hidetsugu makes three maul attacks.
Maul. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: (2d6 + 5) bludgeoning damage, plus 18 (4d8) fire damage.
Horror Nimbus (Recharge 5-6). The The Mujo Hidetsugu magically emits scintillating, multicolored light. Each creature within 30 feet of the Mujo Hidetsugu that can see the light must succeed on a DC 18 Wisdom saving throw or be frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the nalfeshnee's Horror Nimbus for the next 24 hours.
Reactions
Parry. The Mujo Hidetsugu adds 6 to its AC against one melee attack that would hit it. To do so, the Mujo Hidetsugu must see the attacker and be wielding a melee weapon.

[KittenMagician]

i suggest making him immune to the charmed condition as well as frightened and poisoned. maybe increase his speed a bit (40ft?). also make the horror nimbus do some damage (4d6 psychic?) since once they succeed on the save and become immune to the fear effect there is really no point to it having a 5-6 recharge. this would also catch a little bit more of his "heartless"ness and the hatred he harbors