Legendary Resistance (3/Day). If the giant fails a saving throw, it can choose to succeed instead.

Spellcasting. The giant is a spellcaster. Its spellcasting ability is Intelligence (spell save DC 15, +6 to hit with spell attacks). The giant has the following warlock spells:

Cantrips (at will): Blade ward, Eldritch blast

1st level (3 slots): Armour of agathys, Witch bolt, Hellish rebuke

2nd level (2 slots): Hold person, Misty step

Multiattack. The giant makes two flail attacks.

Flail. Melee Weapon Attack: +9 to hit, reach 13 ft., one target, 3d12+6 bludgeoning damage.

Bow. Ranged Weapon Attack: +9 to hit, range 60/450 ft, one target. 3d10+6 piercing damage.

Frightful Presence. Each creature of the giant's choice that is within 120 feet of the giant and aware of it must succeed on a DC 18 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the giant's Frightful Presence for the next 24 hours.

Shield block. +2 AC for 1 turn.

The giant can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The giant regains spent legendary actions at the start of its turn.

Detect. The giant makes a Wisdom (Perception) check.

Dark Magic. Cast a cantrip.

Dark Shell (Costs 2 Actions). The giant gains +3 AC and gains resistance to radiant damage for 1d4 turns and has a darkness spell cast, centered on it for the effects duration.

Dark Recovery (Costs 3 Actions). The giant uses the darkness within to repair its armour, regains 1d12+15 hit points.