Snapthorn

A whip is a summoner's targeting tool first and a weapon second. Cracking it at something marks that enemy, and your minions drop whatever they were doing and go for the mark. This one adds a short attack speed buff on top, and the timer restarts every time you land a hit, so the rhythm is to keep swinging without breaks rather than to alternate with another weapon. Pause for a moment and you fall back to your base swing rate and have to build the buff again from nothing.

Each extra enemy caught in one crack takes noticeably less, so a whip sweeping a crowd is doing far less work than the number on the page suggests. The reach is also short, which means anything that closes fast will be standing inside you before your minions react. Treat the poison as incidental. Later whips like Spinal Tap and Durendal replace it, but until then the speed buff is worth more than the raw damage it lists.