It's time for the Atomic Age to get it's mage (of evil)! I apologize for not being able to create any concept art. I am woefully inept at creating anything even slightly artistic; hopefully my idea will be creative enough to make up for that.
I envision the Master of Evil wielding a vibrant green cooling rod (that grows brighter as he levels or aquires more AP) capped with a crystal that barely restrains a surging molecule of Uranium-238.
His garb could be a radiation suit perhaps like the one Marty Mcfly wears in Back to the Future or one of the more fashionable and sleek black ones? I am somewhat against a yellow primary. I think it'd be much more chic to have the primary be black and adorning nuclear symbols (like on his cape and gloves) be yellow.
His spells and animations (as well as perhaps a dance and joke) are the meat of the creativity, and also the hardest part.
Q - Baleful Strike: Should likely be a very low-scale nuclear explosion or perhaps a nuclear powered laser blast shot from the tip of his cooling rod staff. It'd likely be a nice Neon-green.
W - Dark Matter: An excited ball of nuclear waste rains down splashin everything with lethal doses of radiation and leaving a trailing nuclear miasma.
E - Event Horizon: A quarantine zone erects to keep the contaminated contained. Silvery-black Nuclear Power Plant Cooling Towers could erect at the points with traces of the miasma effect from Dark matter contained within.
R - Primordial Burst: As if you have to ask, this has to be a full on Nuclear Explosion. I want this to be cast resulting in WW3. The landcape must be scarred, the terrain should look deadened and far worse for wear. Dusting effects are a must.
His passive: Little radioactive symbols and some (mellow) geiger clicking sounds can pop up everytime he gains AP.
I'm so excited I'm at Critical mass.