Dust Bringer Fire Giant

Dust Bringer Fire Giant CR: 10

Huge giant, lawful evil

Armor Class: 20 (Plate Mail +1)

Hit Points: 185

Speed: 40 ft

STR

26 +8

DEX

12 +1

CON

24 +7

INT

18 +4

WIS

14 +2

CHA

13 +1

Saving Throws: Dexterity +5, Constitution +11, Intelligence +7

Skills: Athletics +12 Perception +6 Arcana +8 Religion +8

Damage Immunities: Fire

Senses: Darkvision = 120 ft Blindsight = 60ft

Languages: Giant, Orc, Draconic

Challenge Rating: 10

Proficiency Bonus: +4

The Fire Giant Dust Bringer is an 11th level spell caster. It's spellcasting ability is Intelligence (Spell Save DC 16, +8 to hit). It knows the following spells:
Cantrips: Control flames, Create Bonfire, Firebolt
1st level (4 slots): Burning Hands, Fog Cloud
2nd level (3 slots): Pyrotechnics, Scorching Ray
3rd level: (3 slots) Fire Ball, Blinding Smite, Counterspell
4th level: (2 slots) Wall of Fire, Fire Shield
5th level: (2 slots) Sandstorm*

Gigantic Pyromancy Whenever the Giant casts any spell with a range, it is doubled, and it can add they're intelligence modifier (+4) to any fire-based spell
War Caster: The Giant has advantage on Constitution saving throws to maintain concentration and can cast spells with somatic components while wielding any weapons
Elemental Affinity: The Giant can ignore any resistance to fire. Anything immune to fire is now resistant to any fire damage.
Molten Body: At the start of a creature's turn, when a creature hits the giant with a melee weapon, or enters within 10 ft of the Giant, they take an additional (2d10) fire damage

Sandstorm

6th-level transmutation

Casting Time: 1 action

Range: 100 ft. (50-foot radius, 50-foot tall cylinder)

Components: V, S, M* (a handful of sand, which the spell consumes)

Duration: 1 Minute

You cause a sandstorm to emerge at a point within 100 ft. that you can see in a 50-foot radius, 50-foot tall cylinder. Everything in the area is considered heavily obscured. For the duration, the sandstorm rages, causing all creatures in the spell’s area without blindsight or tremorsense to have disadvantage on all attack rolls and Dexterity saving throws. All ranged attacks originating from outside the sandstorm that are targeting a creature, object, or space that are in the sandstorm are done at disadvantage, unless the attacker has blindsight or tremorsense and is close enough to the target to sense them.
A creature that starts their turn in the Sandstorm must succeed on a Constitution saving throw or be blinded until the end of their next turn.
You can use a bonus action to move this spell’s area in 30 ft. in any direction.

Actions

Multi-attack: The Fire Giant Dust Caller can make 2 attacks with the maul, 1 with a maul and 1 with a Molten Rock, or 2 with the Molten Rock
Forge Maul: Melee Attack, +13 to hit, reach 10 ft, Hit: (4d6 + 8, plus 2d8 fire damage)
Molten Rock: Ranged Weapon Attack, +13 to hit, range 60/240, one target, 25 (3d10+8) plus 12 (4d6) fire damage

Reactions

Counterspell: As a reaction upon seeing an enemy cast a spell, the giant can attempt to cast Counterspell to interrupt the affect using a spellslot of 3rd to 5th level.

What stands before you is a towering figure with molten skin. It's armor seems to be made of a wrought-iron-like metal with all manner of Giant runes carved into it. In one hand, arcane power seems to surge around in a cyclone, and in the other is a massive maul-like hammer with veins of molten lava flowing through it. Her eyes are the color of the desert, and her smile and demeaner seems to display a sense of intelligence beyond that of most of her kin. With a flick of her rist, the arcane storm expands outward, and soon the entire area is filled in a raging sandstorm. All you can see is the silhouette of the Giant and the burning eyes staring down with malice.