Honestly, these guys are harder than bosses, they can appear in pretty much any level and they just shred my team to pieces. Ridiculously OP compared to other bots their level and don't even start me on when they appear (as the RNG does to me so often) with Leader or Command bots.
I'm eagerly watching Misery's expert level LP and hoping that he comes up against these guys soon, but he's having ISP/modem problems and the episodes, unfortnately, aren't getting uploaded regularly.
I'm playing on Expert level. Some of the strats I've tried are turrets (fodder for the Doombots +to power on hit), mines (somewhat effective but not enough to go around), gamma laser (again, effective but limited by ammo count and layout), and stealth (will happily avoid Doombots where possible and where level objectives allow). My main problem is where they spawn in massive numbers (often togther). Perhaps it's just a design decision that they are there to make levels completely unplayable every now and then?
<Sigh> I'd take Vipers or Claws (or pretty much any boss type) rather than these guys...