This is the ID used for the Wild Imp(s) summoned by Demonic Calling. Looks like Blizzard is really fond of reusing IDs... =/
Anyway, it casts Fel Firebolt. The NPC has 10 energy (which does not replenish), so once the basic ability has been used 10 times, the imp will despawn. A demonology warlock can have multiple wild imps out, however.