User blog comment:JmLyan/Jace, the Mind Sculptor/@comment-3974211-20130408163140

Mana burn is considered "antifun" within the League of Legends. As such, I would recommend tweaking his Q and E. For example, Kassadin and Wit's End's mana burn was changed to on-hit magic damage. If you want a counter-caster mechanic, perhaps
 * "Jace deals magic damage and applies concussion. After the target's next successful ability, they becoming silenced for 3 seconds."
 * "Jace deals magic damage to his target and applies Mana Leak for 6 seconds. Mana leak halves the mana regeneration effects." (although I think this would still classify as antifun)
 * "Jace blasts his target dealing magic damage. Residue from the blast falls to the floor, which an ally can pick up to replenish mana."

Maybe make Fact or Fiction apply concussion in an AOE?

Also, I think making Jace use Energy instead of Mana would be more appropriate to his Omniscience mechanic. So, 200 Energy and 50 Energy Regen/5 seconds. Call it something else if you will; but I think allowing Jace to benefit from mana items is a trap mechanic. Omniscience would be tweaked to say: "When a nearby allied champion uses an ability that costs less mana than Jace's current energy, Jace pays the cost instead. Jace will not regenerate energy if he has dealt or received damage int he last 5 seconds."

It's a fairly decent idea. I know he's based on Magic the Gathering, but you could do with changing the name to something that isn't so similar to.