Eh, maybe the lightning on his hands is the precursor to the thunder. At first, I thought it made no sense for him to have Sonic either, but Thunder is actually an auditory effect.
Thunder is the sound caused by lightning. Depending on the distance and nature of the lightning, thunder can range from a sharp, loud crack to a long, low rumble (brontide). The sudden increase in pressure and temperature from lightning produces rapid expansion of the air surrounding and within a bolt of lightning. In turn, this expansion of air creates a sonic shock wave, similar to a sonic boom, which produces the sound of thunder, often referred to as a clap, crack, or peal of thunder. The distance of the lightning can be calculated by the listener based on the time interval from when the lightning is seen to when the sound is heard.
Yea if it's gonna be a sound damage elemental u need a more appropriate sprite. The current one is misleading. I suggest this. "SONIC BOOM!"
By that logic, all champions should have sonic attacks, because the contact of any 2 objects causes a shockwave.
Lighting creates thunder. If you see lightning, you can count the seconds until you hear the thunder to tell how far away it is. EDIT: Dammit prof, ya beat me to it, just noticed. Sigh.