Sources
CR
Type
Size
Alignment
Movement

Vlazok

Large Fiend (demon), Chaotic Evil

Armor Class 17 (natural armor)
Hit Points 136 (16d10 + 48)
Speed 30 ft., climb 30 ft.
STR
21
+5
DEX
18
+4
CON
16
+3
INT
6
-2
WIS
9
-1
CHA
9
-1
Saving Throws STR +9, CON +7
Skills Perception +3
Damage Resistances cold, fire, lightning
Damage Immunities poison
Condition Immunities Charmed, Exhaustion, Frightened, Poisoned
Senses darkvision 120 ft., passive Perception 13
Languages Abyssal, telepathy 120 ft.
Challenge 11 (7,200 XP)

Traits

All-Around Vision. The vlazok can't be surprised.

Blood Frenzy. The vlazok has advantage on melee attack rolls against any creature that doesn't have all its hit points.

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

Spider Climb. The vlazok can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Actions

Multiattack. The vlazok makes two Gore attacks.

Gore. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit:23 (4d8 + 5) piercing damage, and if the target is a Large or smaller creature, it has the prone condition.

Bonus Actions

Stomp. Melee Weapon Attack: +9 to hit, reach 5 ft., one prone creature. Hit:27 (4d10 + 5) bludgeoning damage.

Lore

Skeletal, quadrupedal horrors, vlazoks are particularly suited to battlefield cleanup in the Outer Planes. They love to stomp across battlefields after the fiercest fighting is over, trampling survivors and crushing pockets of resistance. When vlazoks anticipate an influx of enemies, these demons jump on them from above to crush them.