Fiendish Blessing. Isaac’s AC includes his Charisma bonus.

Innate Spellcasting. Isaac’s spellcasting ability is Charisma (spell save DC 15). Isaac can innately cast the following spells, requiring no material components:

3/day each: alter self, command, detect magic

1/day: plane shift (self only)

Grim Harvest (1/Turn). When Isaac kills one or more creatures that aren’t constructs or undead with a spell of 1st level or higher, he regains hit points equal to twice the spell’s level, or three times its level if the spell belongs to the School of Necromancy.

Undead Thralls. Whenever Isaac creates an undead using a necromancy spell, the creature’s hit point maximum is increased by 13 and adds 4 to its weapon damage rolls.

Inured to Undeath. Isaac’s hit point maximum can’t be reduced.

Spellcasting. Isaac is a 13th-level spellcaster. His spellcasting ability is Intelligence (spell save DC 16, +8 to hit with spell attacks). Isaac has the following wizard spells prepared:

Cantrips (at will): mage hand, thunderclap, light, shocking grasp, toll the dead

1st level (4 slots): alarm, mage armor, silvery barbs,

2nd level (3 slots): invisibility, see invisibility, rime’s binding ice, mirror image

3rd level (3 slots): counterspell, fireball, sending

4th level (3 slots): blight, greater invisibility, private sanctum

5th level (2 slots): negative energy flood

6th level (1 slot): contingency (usually “cast greater invisibility when I am reduced to one-third or less health”), create undead

7th level (1 slot): power word pain

Arcane Recovery (1/Day). When Isaac finishes a short rest, he can choose expended spell slots to recover. The spell slots can have a combined level that is equal to or less than 6.

Multiattack. Isaac makes two melee attacks or uses his Fire Ray twice.

Spear. Melee or Ranged Weapon Attack: +8 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 7 (1d6 + 4) piercing damage, or 8 (1d8 + 4) piercing damage if used with two hands, plus 3 (1d6) fire damage.

Fire Ray. Ranged Spell Attack: +7 to hit, range 120 ft., one target. Hit: 10 (3d6) fire damage.

Fiendish Charm. One humanoid Isaac can see within 30 feet of him must succeed on a DC 15 Wisdom saving throw or be magically charmed for 1 day. The charmed target obeys Isaac’s spoken commands. If the target suffers any harm from Isaac or another creature or receives a suicidal command from Isaac, the target can repeat the saving throw, ending the effect on itself on a success. If a target’s saving throw is successful, or if the effect ends for it, the creature is immune to Isaac’s Fiendish Charm for the next 24 hours.