Since the players converted Kul-Kevoth to their cause relatively straightforwardly they didn’t end up sacking/exploring the palace. So the Black Seer’s were mentioned but never encountered in combat. Purely for reference.
BLACK SEER
Medium humanoid (human), chaotic evil
Armour Class 16 (scale mail)
Hit Points 123 (11d8+70)
Speed 30 ft.
STR 11 (+0) DEX 14 (+2) CON 16 (+3)
INT 13 (+1) WIS 17 (+3) CHA 20 (+5)
Saving Throws Con +5, Wis +6, Cha +8
Skills Insight +6, Perception +6, Religion +4, Stealth +5
Senses darkvision 60 ft., passive Perception 16
Languages Common, Hallit
Challenge 10 (5,900)
Lucky in Death. The Black Seer is lucky and seems to escape terrible accidents through sheer luck, until that luck runs out. The Black Seer has advantage on saving throws against death effects, disease, mind-affecting effects, poison, sleep and being stunned. However, if the Black Seer rolls a natural 1 with both die he instantly dies via some horrible (and implausible) accident.
Wind Walker. The Black Seer can walk on air. As a bonus action the Black Seer may spend his move ascending up to his move at a 45 degree angle as if climbing invisible stairs.
ACTIONS
Multiattack. The Black Seer makes two attacks and a necrotic burst when .
Light Pick. Melee Weapon Attack: +6 to hit, reach 5 ft., one target.
Hit: 4 (1d4 + 2) piercing damage plus 17 (5d6) poison damage.
Necrotic Burst (Natural Odd Number). All creatures in a 30 ft. cone suffer 15 (3d10) necrotic damage and the Black Seer heals for half the total damage. A successful DC 16 Constitution save halves the damage.
TACTICS
Before Combat A Black Seer casts air walk, false life, shield of faith, and bear’s endurance before combat. In addition, she has already cast scrying once and enter image once.
During Combat A Black Seer avoids melee combat entirely, focusing her spells against foes for as long as possible. She uses her wand of inflict serious wounds if forced into melee. She retreats to safety to heal back to full hit points once reduced to fewer than 40 hp.
Morale If unable to retreat and heal, a Black Seer fights to the death
GEAR
Combat Gear scrolls of cure critical wounds (2), wand of inflict serious wounds (12 charges); Other Gear light pick, amulet of natural armor +1, cloak of resistance +3, headband of alluring charisma +2, ring of force shield, ring of protection +1