On the final mission for my Insanity run.
Defense Matrix + Tech Armor has become one of my favorite ability combinations. The combined defense boost and the 100% shield recharge from purging DM makes you even more of a unkillable murder machine than in ME2.
Your cooldowns do suffer a bit from having both up, but they're under 3 seconds each for me and I usually didn't take the recharge boosts on the actual skills.
I used SMGs and Heavy Pistols. The Locust and the Paladin are a great combo. I imagine this build could do a lot of damage with a Shotgun as well. Might try it in a NG+.
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Gamertag/PSN-Murphiroth
"Would have liked to run tests on the seashells..."