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.
The base cooldowns on each of The Storm Sphere's basic abilities are reduced by 0.75 seconds every time he casts them. This effect lasts for 3 seconds after the spell comes off of cooldown, and can stack up to 6 times.
COST: 65 mana
Active: The Storm Sphere deals magic damage in an area around it.
Toggle: Spell hits deal 40% damage over 2 seconds to enemies within a radius 50 (+ 200% of target's armor) of the target they hit, and grant Storm Sphere a 10% movement speed boost which stacks up to three times.
Toggle: The Storm Sphere drains mana every time it is attacked to deal damage and gain a small amount of armor and magic resistance. The armor and magic resistance can stack up to 10 times. All stacks are lost when the ability is toggled off.
Recoil Damage: 20 / 35 / 50 / 65 / 80 (+ 20% AP)
Armor and MR per stack: 2 / 3 / 4 / 5 / 6
Max Armor and MR: 20 / 30 / 40 / 50 / 60
COST: 70 mana
Active: The Storm Sphere releases a burst of electrical energy, dealing damage to the first enemy unit it hits, and then instantly jumps to all enemy units in a small range. This continues indefinitely, but can only effect an enemy unit once.