Thunder Palace

You conjure 8 bolts of lightning spaced at equal distances along the edge of a 15 ft. radius cylinder around you. This cylinder is 50 ft. tall and you have to have sufficient space to conjure these bolts or the spell fails. Whenever you conjure this spell you may pick any number of creatures to be unaffected by it.

Whenever someone enters enters or exits the cylinder you can use a reaction to for them to make a Dexterity saving throw taking 8d10 lightning damage on a failed save or half as much on a successful one. This expends one of the 8 bolts of lightning that was conjured at the beginning of the spell. In addition whenever a creature starts its turn inside the cylinder it takes 1d8 lightning damage for each remaining bolt of lightning.

As a bonus action on your turn you can fire one bolt of lightning at a target within 300 ft. expending one of the 8 bolts conjured when you casted this spell. When you do this make a ranged spell attack roll against the target. Upon a hit they take 8d10 lightning damage. 

If this spell is cast outside in a thunder storm the spell conjures 4 additional bolts of lightning.