I find the following set up for a Human Engineer to be working well:
- Human Engineer
- Incinerate with area blast upgrade
- Overload with both chain blast upgrades & shock organics upgrade
- Drone with shield/attack boost and chain attack upgrade
- Assault Rifle (M8 Avenger X has been doing fine for me)
- Cryo ammo upgrade
You are not dealing high damage to a single target, but instead dealing huge damage distributed amongst enemies at once.
Your crowd control, hitting groups of enemies at once, further boosted by the Cryo ammo allowing you to easily set up frozen targets for Tech Combos with Incinerate, again nuking areas of predamaged opponents.
I can clear, or at least hold off, whole hordes single handed if need be.
Its also a very team play orientated build, as your thinning the herd making it easier for other to to pick off wounded foes, slowing down enemies for Infiltrators to headshot, stripping shields for Vanguards to massacre in Bitoic charge, and the drone is great for holding the attention of larger foes whilst you collectively pond them - seriously - target a drone on a Banshee or Brute and watch them stand and fight it!