I have done a few tries on Levi EX as ot and have some trouble getting around the stunlocking of the mage add.
From my point of view it seems a win or wipe is dependant on whether I can stop the mage's castings or not.
On the first mageadd I build up with the first two moves of the RoH combo on Levi's tale, and then on mage - RoH - RoS - FB - SW - SB - stun - FB - stun - SB - stun

On the second I start with provoke - shield lob - RoS - FB - sw - SB - stun - FB - stun

Sometimes it works, sometimes it doesnt.... Sometimes he is dead just before the cast finishes. Is that a sign that I didnt stunlock him and the dps is very good, or did I do everything right and the dps was just barely enough?
Is there anything I do wrong, or is there something else?
Too low skillspeed? (mine is 391)
Too low accuracy? (mine is 478)

I appriciate every kind of advise about this.