Multiattack

The jotun can use its Frightful Presence. It then makes three Greatclub or Rock attacks.

Greatclub

Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 28 (4d8 + 10) bludgeoning damage plus 27 (6d8) cold damage.

Rock

Ranged Weapon Attack: +17 to hit, range 60/240 ft., one target. Hit: 32 (4d10 + 10) bludgeoning damage plus 27 (6d8) cold damage.

Frightful Presence

Each creature of the jotun's choice within 120 feet of the jotun and aware of it must succeed on a DC 20 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 jotun's Frightful Presence for the next 24 hours.

Icy Sweep (Recharge 5-6)

The jotun swings its ice-coated greatclub in a wide arc. Each creature within 20 feet of the jotun must make a DC 23 Dexterity saving throw. On a failure, a creature takes 36 (8d8) bludgeoning damage and 54 (12d8) cold damage and is pushed up to 15 feet away from the jotun and knocked prone. On a success, a creature takes half the damage and isn't pushed or knocked prone.

Spellcasting

The jotun casts one of the following spells, requiring no material components and using Wisdom as the spellcasting ability (spell save DC 20): At will: earthquake, speak with animals 3/day: bestow curse, gust of wind 1/day: divination