This build utilises out of cover damage, suppression and seriously ripping through enemies at both long and short range.
When approaching groups of NPC, place your Support Station, Flashbang the group and then unleash with the Big Alejandro - trying to ping the head for pulse damage. 9/10 you'll have destroyed the group before they snap out of stun.
If the enemies can shake the stun before their demise, you should easily be able to suppress them, gaining increased headsheat damage. At this point, run towards the enemies, switch to The Showstopper and pump shots in to the crouching enemies heads or the standing/running few looking for new cover.
Your 20% Health on Kill should offer you enough sustain to help during engagements, whilst dropping and popping the Support Station can give you a 33% burst of health during clutch times.
When possible, finish off enemies or reds/purples with your Sawed Off to proceed Predatory and Determined to bring back skills quickly and offer some long term health increments.
As a lovely bonus, I've even held my own against numerous Rogues at both long and short range.
(The added 20% DZ credits is just the icing on the cake)