I've tried this a few times now on my trader Zanda and each time I've been able to prevent the Beast from casting his big damage shield. A few weeks ago I was in a short hand Omni pug and I was told to dish out as much nano drain as I could, so this is something they already knew

The aim is to always have plagiarize notum, forced bankruptcy and GTH running. GTH needs your nano pool to be well down to suck from the target so always run Eviserate Defense, Attenuate Defense and Abolish Polonium before running GTH. So in the normal busy trader attack cycle which I'll list below make sure the nano drains are always on the go.
Normal attack cycle:
procs: unopened letter, accumulated interest and Bracer Brother of Malevolence always running
PN, FB
Divest skills (Nanite Improved)
Plunder Skills (Nanite Improved)
Divest damage (short recast)
Industrial Sabotage (short recast)
Corporate Protection (short recast)
Pawnbroker's armor (cast once)
Draw AC (invasive) (cast once)
ED, AD, AP, GTH, Your enemy's enemy is your friend.
Mash keybinds in between as a few of the common attack perks drain nano and attack target nano skills..
Rinse repeat over and over and no shield. I'd also recommend that the trader stays on beast when adds arrive... GL