As of yet, no known Shockmancer has been introduced.
However, Caesar mentions that Carpool has a Shockmancer and he visited the city of Chocula before it was attacked by Transylvito. The Carpudlian Shockmancer bulked up the tower air defenses prior to the battle.
Real World References
When casting the SpellErf-b1-p126 Sizemore mentions names of well known pictures or videos on the Internet, which are disturbing for viewers, and difficult to get out of one's head; colloquially, these pages are known as shock sites. NSFW sound effect is an abbreviation for Not Safe for Work, which would certainly apply to shock sites in general. 4Chan sound effect as a secondary sound effect accompanying the explosion is an image site well known its "execrable" standards as well as for posting and producing shock images.
The "Flash mob" ability used by the Archons is a double-entendre of real-world references. The term refers to any group of people who assemble suddenly in a single location to perform some action, as a group of Archons did over Expository Bridge. Once assembled, the Archons "flashed" (i.e. exposed parts of their bodies to) the forces of Jetstone to stun them into not noticing the casting of a veil in the adjacent hex. Thus the tactic was both a flash mob and a mob that flashed. The effect of stunning a target could also be a reference to a "flash-bang" grenade which is used by law enforcement and military to blind, disorient, and stun opponents.