Primordial Patron

You have made a pact with a titan from the inner planes. Your patron's motivations are usually simple: to create anarchy and chaos in the planes and seek to use their warlocks as a way to destabilize the worlds. Entities that you may be your patron are princes of elemental evil, Dendar the night serpent, Ubato the deceiver, ancient Djin and some powerful elementals. 

Elemental Backlash

Starting at 1st Level, the elemental magic gifted to you by your patron can explode out of you as a response to pain. Whenever you are hit by an attack from a creature within 5 feet of you, you can use your reaction to deal Acid, Cold, Fire, Lightning, Poison or Thunder damage to the creature. The extra damage equals your level. Once you use this feature, you cannot use it again until you finish a short or long rest. 

Expanded Spell List

Your Patron lets you choose from an expanded list of spells when you learn a Warlock spell. The following spells are added to the Warlock spell list for you. 

1st: Entangle, Chromatic Orb

2nd: Enlarge/Reduce, Augury

3rd: Dispell Magic, Meld into Stone

4th: Death Ward, Conjure Minor Elementals

5th: Conjure Elementals, Gaes

Armor of Chaos

Beginning at 6th Level, the magic of your patron manifests as an elemental shield that defends you from harm. You gain temporary hit points equal to half your level whenever you finish a short or long rest. You can only have one set of temporary hit points from this feature at a time. 

Colossal Form

Starting at 10th Level, you can use a bonus action, you can grow in size, becoming a massive form of swirling power. Your size becomes large unless you were larger. Your speed becomes 40. Once on your turn you can deal extra damage equal to your charisma modifier whenever you hit with a weapon or spell attack. The damage can be Acid, Cold, Fire, Poison, Lightning or Thunder. This transformation lasts until the end of your next turn. Once you use this feature, you cannot use it again until you finish a short or long rest. 

Primordial Storm

Beginning at 14th Level, you target a point you can see within 30 feet of you. All creatures within 5 foot sphere, centered on the point you chose must make a Dexterity saving throw against your spell save DC, taking 5d10 Acid, Cold, Fire, Poison, Lightning or Thunder damage on a failed save or half as much on a successful save. Once you use this feature, you cannot use it again until you finish a long rest.