So far my two favorite builds:
Incinerate - burning, impact, double shot.
Charge - damage, power synergy, shock.
Nova - damage, armor, seismic.
Dhan Shotgun - level shotgun skill for larger clips then research and make this shotgun with the vintage heat sink. You'll have unlimited ammo and a two round clip that auto-reloads every three seconds -- the level 5 gun does right around 1000 damage, so you really don't need many shots.
So you incinerate to prime, charge to detonate (which also recharges your shields), and nova. If anything is still standing (guys with shields/armor) two shotting them with the shotgun should put them down.
Overcharge - damage, charged overload (additional chain), maximum charge.
Lance - damage, anti-sheild, knockdown.
Singularity - radius, recharge, exploding.
P.A.W. assault rifle - the electric modifier. Decent range, excellent accuracy, could change out for sniper rife but I'm planning an eventual play-through with a sniper/stealth build, so...
This is the ranged build specializing in remnants. Even though it doesn't tell you, Overcharge actually primes targets (and kind of stuns them for a few seconds) -- so you charge that up and hit 3 guys with it, Lance to detonate, then toss out the Singularity to capture enemies and wait for the other two to recharge. Anything captured in the Singularity will be primed for the next barrage and once you do the next Overcharge/Lance combo trigger the Singularity explosion. This works really well for taking out the observer assholes' shields with the first two hits then disabling them and anything near them while waiting for the kill. Rifle is just extra damage while waiting for the combos to recharge. I suppose you could substitute pretty much any long-range detonator for Lance, but it hits hard, has infinite range, and is in the biotic tree which I specialized in the most.
I use the Explorer profile for both because of the biotic damage increase and fucking awesome biotic blink, but Sentinel works well too for the combo damage.
