Why isn't this working?! (instakill)

Create Chasm (Earthmover or Royal Geomancer) near enemy champion without flying + knockback (Avalanche, Stone Bomb, Slam etc.) should be instakill, right? So my question is - Why isn't this working?! Like Vergil once said - "Is there something missing? Must more blood be shed?"

 

If it has any AP it will use that to keep itself from falling.

 

Are u serious? -_-

 

They did make that change since it was to easy to cliff dive champs otherwise.

 

Since i remember it was in this manner

 

Yeah, this change was made something like two years ago if I remember correctly since SP players would use avalanche on units that deployed on their font's edge (or at least this was the most memorable complaint that I remember). So now you have to knock them back two or three times to chasm them.

 

The real hate started with gale force. Knockback 2 spaces from a chasm and get a kill. Also when gale force gave flying for 1 turn