Storm Giant

Huge giant, chaotic good

Armor Class 16 (scale mail)
Hit Points 230 (20d12 + 100)
Speed 50 ft., swim 50 ft.

Saving Throws Str +14, Con +10, Wis +9, Cha +9
Skills Arcana +8, Athletics +14, History +8, Perception +9
Damage Resistances cold
Damage Immunities lightning, thunder
Senses passive Perception 19
Languages Common, Giant
Challenge 13 (10,000 XP)

Amphibious. The giant can breathe air and water.
Innate Spellcasting. The giant's innate spellcasting ability is Charisma (spell save DC 17). It can innately cast the following spells, requiring no material components:
At will: detect magic, feather fall, levitate, light
3/day each: control weather, water breathing

Actions

Multiattack. The giant makes two greatsword attacks.
Greatsword. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 30 (6d6 + 9) slashing damage.
Rock. Ranged Weapon Attack: +14 to hit, range 60/240 ft., one target. Hit: 35 (4d12 + 9) bludgeoning damage.
Lightning Strike (Recharge 5–6). The giant hurls a magical lightning bolt at a point it can see within 500 feet of it. Each creature within 10 feet of that point must make a DC 17 Dexterity saving throw, taking 54 (12d8) lightning damage on a failed save, or half as much damage on a successful one.