Legendary Resistance (3/Day): If Hamatu fails a saving throw, he can choose to succeed instead.
Defiling. When Hamatu stands in an area with living plants or creatures, he can drain their energy to power his spells, treating them as if cast with a spell slot one level higher than he actually spends. Hamatu can also cause each creature within 5ft of to make a Constitution saving throw DC 17 or take 1d6 necrotic damage. If he does do, and at least one creature is damaged by this feature, he has advantage on the attack roll of the spell, if it requires one, or else targets of the spell he is casting have disadvantage on their saving throw. Also, he can reroll any of the die for damage, using the second result even if it’s lower. When he uses this feature, all plant life within 5ft of him turns black and withers, and he cannot use this feature in an area that has been defiled already (unless there are living creatures to defile).
Blood Magic. Hamatu may use his raze feature without expending a spell slot. Instead of casting a spell, he regains 2d8 hit points, plus 1d6 hit points for each creature within 5 feet that fails the Constitution saving throw.
Spellcasting (Human Form). Hamatu is a 20th-level spellcaster. His spellcasting ability is Charisma (spell save DC 20, +10 to hit with spell attacks). The sorcerer-king has the following sorcerer spells prepared:
Cantrips (at will): chill touch, fire bolt, mage hand, minor illusion
4th level (3 slots): Evard’s black tentacles, stoneskin
5th level (3 slots): Bigby’s hand, wall of force
6th level (2 slot): Flesh to stone, globe of invulnerability, disintegrate
7th level (2 slot): symbol
8th level (1 slot): Abi-Dalzim’s horrid wilting, mind blank
9th level (1 slot): weird
Keen Smell (Lion Form). Hamatu has advantage on Wisdom (Perception) checks that rely on smell.
Pounce (Lion Form). If Hamatu moves at least 20 ft. straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 19 Strength saving throw or be knocked prone. If the target is prone, the Lion can make one bite attack against it as a bonus action.
Running Leap (Lion Form). With a 10-foot running start, the lion can long jump up to 40 ft..
Multiattack. If in human form, Hamatu makes three staff attacks. In lion form, he uses his Frightful Presence, and then makes three attacks: one with its bite and two with its claws.
Black Obsidian Staff (Human Form). Melee Weapon Attack: +9 to hit, range 5ft, one target. Hit: 8 (1d8 + 4) bludgeoning damage, plus 13 (3d8) necrotic damage.
Bite (Lion Form). Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 6) piercing damage plus 4 (1d8) poison damage.
Claw (Lion Form).Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: (2d6 + 6) slashing damage.
Lion Roar (Recharge 5-6, Lion Form). The Lion emits a thunderous roar in a 60-foot cone. Each creature in that area must make a DC 18 Constitution saving throw, taking 54 (12d8) thunder damage on a failed save, or half as much damage on a successful one. Creatures that fail the saving throw are also deafened for 1 minute.
Hamatu can take 3 Legendary Actions, choosing from the options below. Only one legendary action can be used at a time, and only at the end of another creature's turn. Spent legendary actions are regained at the start of each turn.
Attack: If in human form, Hamatu makes an attack with his staff. If in lion form, he makes an attack with its claws.
Cantrip: Hamatu casts a cantrip.
Spell (costs 2 legendary actions): Hamatu casts a spell using his Spellcasting trait.
Lion Shape (1/day). Hamatu assumes its Lion form. This has the same effect as the shapechange spell, but its duration is up to 1 hour (no concentration), and he does get the Legendary Actions of the new form.
Ok, so I have created this taking from an online 5e Dark Sun for the defiler sorcerer part, and practically copied the Adult Black Dragon for the Lion form. The issue is created as the creature has 2 hp pools with different AC scores... The dragon part has CR 14, and calculating the CR for the sorcerer part (assuming no Legendary Resistance because they are already counted in the Lion part). The sorcerer has:
Defensive CR= 6 (130hp, 17AC)
Offensive CR=29 : DC 22 Considering the disadvantage on saves and the damage reroll are always active, it's like the DC is increased by 2. The rerolls are also counted, as well as the spells being 1 slot higher.
First Round: 263=10th level Bigby's Hand as Bonus Action (77), Firebolt as Action (27), Horrid Wilting as 2 Legendary(132) Firebolt as Legendary (27)
Hamatu, the Lion of the Desert
Medium humanoid (shapeshifter), chaotic evil ______ Huge beast (shapeshifter), chaotic evil _
Armor class 17 (mage armor) 19 (natural armor)
Hit points 130 (20d6+60) 195(17d12+82)
Speed 40ft. 70ft.___________________ ________
STR DEX CON INT WIS CHA STR DEX CON
18(+4) 18(+4) 16(+3) 14(+2) 16(+3) 20(+5) ______ 23(+6) 18(+4) 20(+5)___
Saving Throws: Con +8, Int +7, Wis +8, Cha +11 Dex +9, Con +10
Skills Acrobatics +9, Arcana +12, Intimidation +11, Perception +8, Persuasion +11, Stealth +9
Damage Resistances Necrotic, Bludgeoning, Piercing, And Slashing From Nonmagical Weapons
Condition immunities Charmed, Frightened
Senses: Darkvision 60ft., passive Perception 18
Languages: Common, Draconic, Infernal, Sylvan
Challenge: 14 (11,500xp)_____________________________________________________________________________
Legendary Resistance (3/Day): If Hamatu fails a saving throw, he can choose to succeed instead.
Defiling. When Hamatu stands in an area with living plants or creatures, he can drain their energy to power his spells, treating them as if cast with a spell slot one level higher than he actually spends. Hamatu can also cause each creature within 5ft of to make a Constitution saving throw DC 17 or take 1d6 necrotic damage. If he does do, and at least one creature is damaged by this feature, he has advantage on the attack roll of the spell, if it requires one, or else targets of the spell he is casting have disadvantage on their saving throw. Also, he can reroll any of the die for damage, using the second result even if it’s lower. When he uses this feature, all plant life within 5ft of him turns black and withers, and he cannot use this feature in an area that has been defiled already (unless there are living creatures to defile).
Blood Magic. Hamatu may use his raze feature without expending a spell slot. Instead of casting a spell, he regains 2d8 hit points, plus 1d6 hit points for each creature within 5 feet that fails the Constitution saving throw.
Spellcasting (Human Form). Hamatu is a 20th-level spellcaster. His spellcasting ability is Charisma (spell save DC 20, +10 to hit with spell attacks). The sorcerer-king has the following sorcerer spells prepared:
Cantrips (at will): chill touch, fire bolt, mage hand, minor illusion
1st level (4 slots): mage armor, magic missile, thunderwave
2nd level (3 slots): phantasmal force, see invisibility
3rd level (3 slots): counterspell, fly, lightning bolt
4th level (3 slots): Evard’s black tentacles, stoneskin
5th level (3 slots): Bigby’s hand, wall of force
6th level (2 slot): Flesh to stone, globe of invulnerability, disintegrate
7th level (2 slot): symbol
8th level (1 slot): Abi-Dalzim’s horrid wilting, mind blank
9th level (1 slot): weird
Keen Smell (Lion Form). Hamatu has advantage on Wisdom (Perception) checks that rely on smell.
Pounce (Lion Form). If Hamatu moves at least 20 ft. straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 19 Strength saving throw or be knocked prone. If the target is prone, the Lion can make one bite attack against it as a bonus action.
Running Leap (Lion Form). With a 10-foot running start, the lion can long jump up to 40 ft..
Actions_________________________________________________________________________________________
Multiattack. If in human form, Hamatu makes three staff attacks. In lion form, he uses his Frightful Presence, and then makes three attacks: one with its bite and two with its claws.
Black Obsidian Staff (Human Form). Melee Weapon Attack: +9 to hit, range 5ft, one target. Hit: 8 (1d8 + 4) bludgeoning damage, plus 13 (3d8) necrotic damage.
Bite (Lion Form). Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 6) piercing damage plus 4 (1d8) poison damage.
Claw (Lion Form). Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: (2d6 + 6) slashing damage.
Lion Roar (Recharge 5-6, Lion Form). The Lion emits a thunderous roar in a 60-foot cone. Each creature in that area must make a DC 18 Constitution saving throw, taking 54 (12d8) thunder damage on a failed save, or half as much damage on a successful one. Creatures that fail the saving throw are also deafened for 1 minute.
Legendary Actions_____________________________________________________________________________________
Hamatu can take 3 Legendary Actions, choosing from the options below. Only one legendary action can be used at a time, and only at the end of another creature's turn. Spent legendary actions are regained at the start of each turn.
Attack: If in human form, Hamatu makes an attack with his staff. If in lion form, he makes an attack with its claws.
Cantrip: Hamatu casts a cantrip.
Spell (costs 2 legendary actions): Hamatu casts a spell using his Spellcasting trait.
Reactions_______________________________________________________________________________
Lion Shape (1/day). Hamatu assumes its Lion form. This has the same effect as the shapechange spell, but its duration is up to 1 hour (no concentration), and he does get the Legendary Actions of the new form.
Ok, so I have created this taking from an online 5e Dark Sun for the defiler sorcerer part, and practically copied the Adult Black Dragon for the Lion form. The issue is created as the creature has 2 hp pools with different AC scores... The dragon part has CR 14, and calculating the CR for the sorcerer part (assuming no Legendary Resistance because they are already counted in the Lion part). The sorcerer has:
Defensive CR= 6 (130hp, 17AC)
Offensive CR=29 : DC 22 Considering the disadvantage on saves and the damage reroll are always active, it's like the DC is increased by 2. The rerolls are also counted, as well as the spells being 1 slot higher.
First Round: 263=10th level Bigby's Hand as Bonus Action (77), Firebolt as Action (27), Horrid Wilting as 2 Legendary(132) Firebolt as Legendary (27)
Second Round: 306=8th level lightning bolt Action (101), Bigby attack bonus action (77), 8th level l.bolt 2 Legendary (101), Firebolt leg (27)
Third round: 290=7th light.bolt (93), Bigby bonus action (77), 7th light bolt 2 legendary (93), firebolt leg (27)
I have decided for CR 20