Medivh will be heading to the Nexus soon and will be shaking the game to its foundation. With Medivh present, teams will have access to a raven form that allows him to zoom all over the map and become invincible in the process. This allows for scouting ability far above that of stealth characters and gives him a chance to harass teams trying to capture points and so on.
Outside of invincibility and his utility as a scout, Medivh is a pushover if attacked so he'll need to be played wisely.
Be sure to check out the Heroes of the Storm Medivh trailer below.