Oathbreaker/Sorcerer - I like that idea. Dragonborn are "Very Naughty Bois" by default ...
As to your char design plans - our suggestions are based upon EA patch 9 plus what is known about 1.0. Come 3.VIII there could be changes to the game we are not aware yet, hence leave margin for "I may have to tweak it"

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Besides distance spells are various "cone" or "touch" spells - like Shocking Grasp - to be used in melee.