Staff of Power. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) bludgeoning damage, or 6 (1d8 + 2) bludgeoning damage when used with two hands. Manshoon can expend 1 of the staff's charges to deal an extra 3 (1d6) force damage on a hit.
Special Equipment. Manshoon wears a black robe of the archmagi and wields a staff of power (both accounted for in his statistics). Roll 2d10 to determine how many charges the staff has remaining.
Magic Resistance. While wearing his robe of the archmagi, Manshoon has advantage on saving throws against spells and other magical effects.
Spellcasting. Manshoon is an 18th-level spellcaster. His spellcasting ability is Intelligence (spell save DC 21, +15 to hit with spell attacks). He has the following wizard spells prepared:
Cantrips (at will): fire bolt, light, mage hand, prestidigitation, shocking grasp
1st level (4 slots): detect magic, mage armor, magic missile, shield
2nd level (3 slots): detect thoughts, mirror image, misty step
3rd level (3 slots): counterspell, lightning bolt, sending
4th level (3 slots): fire shield, greater invisibility, polymorph
5th level (3 slots): Bigby's hand, scrying, wall of force
6th level (1 slot): flesh to stone, globe of invulnerability
7th level (1 slot): finger of death, simulacrum
8th level (1 slot): feeblemind, mind blank
9th level (1 slot): imprisonment, power word kill