This character is designed to be a highly mobile burst damage dealer who gets in, assassinates a target, then leaves the team fight to wait for cooldowns.
Alternatively, he will be very good at cleaning up fights mostly over already and chasing down running enemies.
Background
It was a warm, midsummer's day when Ukkonen came into this world, the last bolt of an otherwise ordinary thunderstorm over the broken lands of a dying world. Ukkonen was the smallest of his elemental brothers and sisters--so small, in fact, that his birth went unnoticed by the storm shepherds herding the newborn bolts to the elemental realm.
Desperate not to be left behind, the tiny bolt rode the last of the storm's fading winds to the shrinking gateway. As the gateway narrowed to a close, he charged forward with all his might, crashing through the dimensional rift with such force that the heavens were made to tremble at the thunderclap.