Ice Devil is a Large fiend with lawful evil alignment and Challenge Rating 14 in the 2024 SRD. This stat block includes AC 18, 228 hit points, speeds, traits, and actions.
Multiattack - The devil makes three Ice Spear attacks. It can replace one attack with a Tail attack.
Ice Spear - Melee or Ranged Attack Roll: +10, reach 5 ft. or range 30/120 ft. Hit: 14 (2d8 + 5) Piercing damage plus 10 (3d6) Cold damage. Until the end of its next turn, the target can’t take a Bonus Action or Reaction, its Speed decreases by 10 feet, and it can move or take one action on its turn, not both. Hit or Miss: The spear magically returns to the devil’s hand immediately after a ranged attack.
Tail - Melee Attack Roll: +10, reach 10 ft. Hit: 15 (3d6 + 5) Bludgeoning damage plus 18 (4d8) Cold damage.
Ice Wall - The devil casts Wall of Ice (level 8 version), requiring no spell components and using Intelligence as the spellcasting ability (spell save DC 17).