tiamat, the dragon queen patron

you have made a pact with tiamat 

your power comes from the 9th layer of hell

Expanded Spell List

The Fiend 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.

Fiend Expanded Spells

Spell Level	Spells
1st	chromatic orb, command
2nd	[Tooltip Not Found], dragon's breath
3rd	fear, fly
4th	charm monster, elemental bane
5th	legend lore, summon dragon

dragonic protection

you AC is equal to 10 + your charisma modifier

breath weapon

you gain a breath weapon attack that deals 3D8 force damage to any creature in a 15 foot cone

Tiamat's blessing

Whenever you finish a long rest you can choose a damage Resistance of acid, cold, fire, lightning, and poison, radiant, necrotic, thunder, psychic, bludgeoning, slashing and piercing damage.

dragonic form

once per long rest you turn into a dragon hydra for one hour while in this form you cannot cast spell, but you can concentrate on spells, you also retain your hit points.  when you reach zero hit points or the duration is over you transform back into your normal state with the same amount of hit points as when you were in your dragon hydra from and you also gain one level of exhaustion