Fiddlesticks. Rework concept, since you arent going to flat out buff him.

Passive: Dread Fiddlesticks applies stacks of dread to enemies within sight range, once per second, up to 4. Stacks last 6 seconds. Each stack causes fiddlesticks to gain 2/3/4 Magic penetration against that target. Damaging an enemy with full stacks causes them to lose 8/12/16 magic resist for 6 seconds, but fiddlesticks will not gain unique magic penetration on them.

Q: Terrify 15/14/13/12/11 second cooldown, 75 mana Target enemy is feared for 1.4/1.6/1.8/2/2.2 seconds, and afterwards is afflicted with Hallucinations for 2 seconds. Hallucinating enemies become unable to distinguish ally from enemy, as every champion appears to be an enemy fiddlesticks.

The hallucinating champion can attack its allies and cast hostile spells at them, and it will appear to damage them from the hallucinating champions point of view, but autos/abilities against allies will not actually damage them, and the cooldowns of hostile spells used on allies are refreshed afterwards. (Dont worry, you wont waste your Veigar ulti on an allied Vayne). Additionally, the health pools of other champions are not viewable if the target is hallucinating. Attacks that come from fiddlesticks will also appear to come from any fakes that are in range of the target.

W: Drain 10/9/8/7/6 second cooldown, 80/85/90/95/100 mana Fiddlesticks tethers himself to a target enemy for up to 5 seconds, dealing 50/80/110/140/170 (+.4 ap) magic damage per second and healing for 60/65/70/75/80% of the damage dealt. Fiddlesticks may move while draining, but is slowed by 50%. If the target moves more than 700 range away from fiddlesticks, the tether is broken.

E: Dark Wind 1 second cooldown, 15/14/13/12/11 second recharge, 70 mana (Ammo system, 1/2/3/4/5 charges max) Fiddlesticks sends a crow to a target unit. Allied champions: It circle overhead for up to 10 seconds. If an enemy champion attacks this ally, the crow flies off to attack that champion. Enemy champions: It deals 50/60/70/80/90 (.45 AP) magic damage to the target and silences it for 1.25 seconds. Enemies who have already been hit by a crow take 50% damage from subsequent hits within 2 seconds, and cannot be silenced more than once every 5 seconds. Enemy Minions/monsters: Deals 60/70/80/90 (.5 AP) magic damage to the target and 50% that to all units surrounding the target and the crow returns to fiddlesticks.

Crowstorm 150/140/130 second cooldown, 100 mana After a 1.5 second channel, fiddlesticks blinks to a target location, dealing 125/225/325 (+.45 ap) magic damage to all enemies around him for 5 seconds. Enemies caught in the AOE instantly proc the MR reduction from dread. Dark wind has its travel time halved in the crowstorm.