An idea I came up with while working on some stuff for another game. Visually it woudl be a sphere of lightning (like kennen's E, but all the time). Functionally it's a DPS mage. His passive only affects the base cooldowns of his abilities, reducing them to a fixed number, unaffected by CDR. A cooldown value based on CDR will still be chosen if it is lower than his current cooldown, but after a certain point (4 stacks) cdr will entirely stop taking effect.
His ultimate is supposed to be a range-independent finisher.