1) Dvar heroes have racial skills for +50% damage every other turn, combine it with ranged skills for +range, +critical chance,and then you can have a bastion with fire burst mod which deals 80+ damage per turn with AoE, I annihilated armies which had almost double power of mine (my 2 stacks were attacked by 4).
2) Sharkarn heroes can use overwatch multiple times per turn, combine it with ranged skills again.

ooeh those are some good insights already thanks

so far, Vanguard has been my most effective faction, mainly due to how insane the Engineer can be with the double turret, and one of them being improved by the Veterancy of the Engineer. Laser Tank getting extra range is also quite strong, allowing them to reach 10 range with the right mods and Engineer's Calibration ability. Engineer + Kill Sequence Mod lets the Rocket Turrets fire a second time if they get a kill.

So, my strongest and easiest to play faction is Assembly. There are several reasons for it:
- they haveaccess to Arc weaponry, one of the strongest weaponry due to stun
- they allow evolved units to instantly be adapted
- they can revive their own units, drastically reducing losses
These advantages are now added with the re-assembler. Give this thing Advanced Reassambling mod, Stun and finally Arc Extension, you have abominations that build stun constructs (which the AI has trouble to handle), as well as AA constructs which bounces towards ground units (and can attack literally anything in order to bounce their attack to ground, including other ground units (own as well) or obstacles).
Even if they fall, they can revive automatically, or another of them revives the fallen. They are the first tech and thus easily gotten. Etc.

With all the new units the various races get, I will see if I get any other deathstacks I will love.

Otherwise, if you want a Sniper Hero, Voidtech is your best bet. So many ranged Boni, especially their ulti...