This idea was originally posted (I think) by Vayne/Vocals once upon a time when this was first discussed. But anyway, here are my thoughts/strat on this CA.
Instead of just waiting for AA bar to reach 3/4, use a CA (I usually use roped shot or searing for shorter cast time) then use backshot (because you can cast while moving back) to get out to proper range, stop, AA should fire, coverage, sniper.
Along with being spec'd perfectionist, this CA will give a good boost to sniper. However, imo, it's pretty situational as already been said. I only use with sniper, when focus aim is up and, obviously, when there is room to joust out.
And, always remember to joust back to sweet spot to maximize dmg because of the distance requirments on the mythical. I'm sure most of you all knew all this, but sometimes I just wanna put my ideas out there to get torn apart

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