The dragon

You have made a pact with a dragon that is as powerful as a god, and is even considered a god. Your patrons aims to strike fear and terror into his enemies by using you as his one man army. This patron is good or evil depending if it's a chromatic dragon or a metallic dragon(go see pages 86-118 of the monster manual for more information about dragons and dragon types).

expanded spell list

You gain an expanded spell list the, spell list is down bellow.

spell level        spells

1st                    chromatic orb, thunder wave 

2nd                   misty step, scorching ray

3rd                    lightning bolt, sleet storm

4th                    ice storm, wall of fire 

5th                    cloud kill, cone of cold 

Draconic immunity

At first level your patron grants you immunity to a certain damage type depending on what type of dragon your patron is, the table bellow will have this information.

[dragon type]           [ damage immunity]

copper, black           acid

green                         poison 

red, gold, brass         fire

blue, bronze             lightning 

white, silver             cold

Dragon caller

At 6th level your connection to dragons gets so strong that you are able to call a dragon for help. On your turn you can call a dragon wyrmling of the same type as your patron your dragons turn is right after yours and once it drops at 0 HP it disappears (after you use this feature you can't use it again until you finish a long rest). At 12th level your dragon becomes a young dragon. 

Draconic mutation

At 10th level your patron mutates your body with draconic features. you grow wings of a dragon, and your flying speed is your walking speed (your flying speed goes up by 5ft every level). You gain a breath weapon that does 5d10 damage the damage type depends on your patrons dragon type (at level 15th it does 8d10, and at 20th it does 10d10).

Draconic presence

At 14th level your patron allows you to strike fear into your enemies. On your turn you can chose to use draconic presence, any hostile creature in a 60ft radius of you becomes frightened of you and can't do anything but run away of you, this lasts for 5 min ( once you use this feature you cant  use it again until you finish a short or long rest).