Sources
CR
Type
Size
Alignment
Movement

Soulstinger Demon

Large Fiend (demon), Lawful Evil

Armor Class 19 (natural armor)
Hit Points 142 (15d10 + 60)
Speed 40 ft., fly 40 ft.
STR
18
+4
DEX
16
+3
CON
18
+4
INT
13
+1
WIS
14
+2
CHA
16
+3
Saving Throws INT +5, WIS +6, CHA +7
Skills Deception +7, Insight +6
Damage Resistances cold; bludgeoning, piercing, slashing, from nonmagical attacks that aren't silvered
Damage Immunities fire, poison
Condition Immunities Poisoned
Senses darkvision 120 ft., passive Perception 12
Languages Infernal, telepathy 120 ft.
Challenge 9 (5,000 XP)

Traits

Devil's Sight. Magical darkness doesn't impede the demon's darkvision.

Magic Resistance. The demon has advantage on saving throws against spells and other magical effects.

Actions

Multiattack. The demon makes three attacks: two with its claws and one with its sting.

Claw. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit:8 (1d8 + 4) slashing damage.

Sting. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit:13 (2d8 + 4) piercing damage plus 17 (5d6) poison damage, and the target must succeed on a DC 14 Constitution saving throw or become poisoned for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Lore

Deep in the desert, far from the protection of the Hekma and the safety of Naktamun, lies a place called Ifnir, the Demons' Nest. The people of Amonkhet believe that the God-Pharaoh banished all the demons of this plane to the desolation of Ifnir as punishment when they rose up in rebellion against him. Some say that the angels carry the worst dissenters into the heart of Ifnir, which is a fate far worse than merely being abandoned amid the scouring sands.