I don't know what a "Tesla coil" is in wow, how it look, or what function it has, but one thing I do know for sure, it's my favorite defense tower in Red Alert wich creates a dangerous electric charge and then unleashes the power in form of a lightning bolt upon the foe that happens to get to close, any human is toast in one hit.
This is the npc that Stalagg and Fuegen (of the Thaddius-Naxxramas encounter) must be near to avoid them going apepoo. This npc is a reference to the Tesla Coil.