Strategy behind Smokescreen vs. Magnetic Trap on higher trials

[Travesty]

Spam smokescreen to minimize incoming damage, and use 2x Maggie to gather/control the mobs instead of mag trap.

[peshta]

Maybe this will help

[Benedicto]

I gambled playing BH this Silver ANB, and I use BH only for dailies and gold farming. Last time I used BH competitively was when the Assault set was still the meta. This ANB I used Magnetic Trap instead of Smokescreen in my last push because I feel more comfortable in grouping mobs while spamming RF and Snipe, but having a hard time in bosses especially Garm, which didn't let me finish TL134, that I could finish her easily if I had Smokescreen, but if I replace Smokescreen, I have to eliminate one mob group at a time because of running in every direction and wastes my time. As a noob in using BH, can any BH expert give some tips in higher trials in using either of the two skills?