Blocking dashes in and out seems very strong for agression and defense. Blocking braum, ali (maybe leona) engage. Blocking lucian, vayne, graves from getting in or out at key moments.
Can also be used to stop a lot of gank potential from roaming mid laners like LB or Fizz along with junglers like xin, lee sin etc.
The ult is just... well.... imagine knocking their ali halfway back to his nexus while you engage on their ADC.