The latent energies of the dreyrugr infused your blood with the power of the Thrall Lords, and you tap into that to channel your arcane abilities.

Class SkillsIntimidate

Bonus Spells:  snowball (3rd), unshakeable chill (5th), ice spears (7th), ice storm (9th), icy prison (11th), cold ice strike (13th), frost mammoth (15th), giant form II (17th), polar midnight (19th)

Bonus Feats: Combat Casting, Dodge, Giant's Jaw, Giant's Limbs, Giant's Stature, Natural Stonesman, Practiced Stonesman, Tosser

Bloodline Arcana: Whenever you cast a spell that deals energy damage, you can change the type of damage to cold. This also changes the spell's descriptors to match this energy type.

Bloodline Powers: The blood of the Thrall Lords runs through your veins, granting you terrible powers.

Jötunthrow (Su)

At 1st level, you can enchant a stone into a throwing stone as a standard action. Unlike a regular throwing stone, these rocks expand into tiny-sized stones that deal 1d6 + your Charisma modifier in bludgeoning damage. At 8th level, the stones you throw are treated as normal throwing stones. You may use this ability a number of times per day equal to 3 + your Charisma modifier.

Giant Traits (Ex)

At 3rd level, your base speed increases by 10 feet. At 7th level, you gain resist cold 10.

Giant's Bellow (Su)

At 9th level, you gain the ability to roar so loudly that it can shake the bowels of even the most courageous opponents. As a standard action, you can unleash a terrifying bellow. All creatures within a 30 ft. radius burst must succeed at a Will save (DC 10 + sorcerer level + Charisma modifier) or become dazed for 1 round and then shaken for an additional 1d6 rounds. This is a sonic, mind-affecting fear effect. You may use this ability once per day at 9th, twice at 15th level, and three times per day at 20th level.

Summon Lesser Giant (Sp)

At 15th level you can let out a terrible call that summons (functioning as summon monster XIII) one of the Thrall Lords' beloved servants—the frost giant. You may use this ability once per day at 15th level and twice per day at 19th level.

Thrall Child (Su)

At 20th level, your bloodline fully manifests and you embrace the dark power you have inherited. Your size increases to Huge, you gain a +8 size bonus to Strength, a +4 size bonus to Constitution, a -4 size penalty to Dexterity, and a +4 natural armor bonus. You also gain the rock catching and rock Throwing racial traits; if you already have these abilities (from racial traits or feats), you instead receive a +5 bonus to Reflex saves, attack rolls, and damage rolls when catching or throwing rocks.