Time for a meeega necro here! I recently fielded a variant of the King Crab that I had never used before, the -009, and I thought I'd share.
The -009 is an interesting 'mech. My friends laughed at me a bit for fielding it. It's not an impressive 'mech, it doesn't have a big oomph like a lot of other assaults (and King Crabs) out there. But it is definitely very functional. Vehicles and infantry don't want to be anywhere near this thing, period. It will kill them at a ridiculously fast pace. And it's an evil machine against other 'mechs too, especially once you take that third ton of MML ammo into consideration. The Plasmas combined with inferno MML rounds mean that any 'mech you face will be getting something like 13 extra heat per turn on average (if all three weapons hit), which forces them to be more conservative with their firepower. At the same time, you're connecting with 2 10-point hits, 2 5-point hits (from Precision or whatever-armed LACs) and more MML missiles or a medium laser or two.
When I played it, it came up against a Thunder Hawk and dismantled it within a few turns. The heat quickly became too much for the T-Hawk to manage, and it got worse from there as I switched over from inferno ammo to standard SRM rounds. The King Crab didn't even lose a single limb from the encounter, and went on to take apart a Schildkrote tank. Well worth the BV - although the Small Cockpit makes it a bit iffy to field (it fell once...not a good thing). Of course, it wouldn't be so easy against a DHS-equipped 'mech, but it showed its worth to me and made me want to field it again.
I got a chance to run this variant in a game last week. I missed the knockout punch that other variants have, but I love anything that runs Plasma Rifles (though sadly there were no infantry or vehicles for me to flambe).
The most ridiculous thing about it was how much trouble the enemy team had hitting it: they were consistently missing on target numbers of 5 or 6. It got so bad that at one point there was open speculation that the pilot was the reincarnation of Morgan Kell.
It inflicted massive damage and even got a kill (a Chameleon picked a very, very bad time to dump its ammo), but ultimately it died after suffering two ammo explosions and a head shot in one round. The pilot was unsurprisingly knocked out (though he did succeed three of the needed rolls), then the immobile mech was kicked in the physical phase, toppling it and killing the pilot. Still, it managed to anchor the center of the map almost entirely by itself and the opposing force was left without enough mechs to turn the tide at that point.
