This is a fairly basic 6 piece striker build with 6k stamina.
Gear is 2 stamina and 3 firearms with a focus on health and crit-chance. I reverse the primary stats on the gear mods (2 firearm and 3 stamina) to hit the 6K stamina threshold. All the mods are crit chance.
For weapons, I run, like everyone, a LVAO-C or Lightweight M4 as the primary. Though I leave the meta with my secondary and run and MDR. I build my stacks with the LVAO-C and then switch to the MDR around the 70/80% mark and do incredible damage; I think the MDR at 100 stacks hits body shots at 115k, add in headshot, armor damage, crit, distracted, responsive, and damage to elites and I've seen 1/2 million hits with the MDR.
In that same vein, I run flash sticky instead of pulse--crowd control plus 18% damage boost with the MDR has proven more effective than the pulse crit damage.
Everything else is pretty standard. Seriously, the MDR is a blast with striker. equip and MDR as your secondary, and do a legendary mission, build the stacks with the M4 (I often focus on shield guys, as hitting their shield, while it doesn't do damage, counts as a hit for the striker stack) and then switch to the MDR and go wild.