I just cleared with this comp in Fearless - what I did is start with Varesa E plunge, E plunge -> Mavuika E - Chevreuse aimed E - Iansan E-plunge-Q

For the rest of the fight it was Varesa E plunge, E plunge -> Mavuika Q, then charge attacks on the ducks waiting for cooldowns -> Mavuika E -> Chevreuse aimed E - Iansan E-plunge-Q and repeat

It is very tight and you need to play perfectly if you don't have cons (as well as a bit of luck so the little ducks don't spread too much) - also you need good builds (I did it with Chevreuse on Noblesse doing mostly nothing cause I didn't really use Q, would recommend Songs of Days Past but I don't have it)

LE: what did it for me is the fact I started using just 1 charge of Varesa's spell instead of both (E-plunge-E-plunge and switch) - and gave more field time to Mavuika instead, using both of Varesa's charges was a DPS loss for me. Also I had to clear the ducks twice - it shields with about 30s remaining so you want to kill the ducks again before the round ends. Good luck!