Vasculash

This is the Crimson half of an early whip pair. The split between the two is minor: this one hits a little harder per crack and gives up a little reach. In practice the reach is what you notice, because a whip only pays for itself when you can mark something without walking into its swing.

Tag damage is the point. Striking an enemy marks it, your minions turn and focus it, and each of their hits lands with the mark stacked on top. A summoner who never picks up a whip is playing at a fraction of the damage available. The one thing to respect is the penalty for sweeping a crowd: the more targets one crack touches, the less each of those hits is worth, so pick a target and stay on it.