Its extremely hard to outheal the plasma blast thingy on phase 1. Its about 5 ticks of 17k damage (20k before stance/talent modifiers).
On 10man our usual tanking setup is 2 prot warriors. With our dps we were getting 3 blasts in phase 1. What worked best for us was first warrior tanks for the first 2 blasts with SW and LS for each and after the second we switch tank (he's tauntable) and the 2nd tank SWs for the 3rd blast.
For phase 2 I disagree on usage of bloodlust. The aoe damage is fairly easy to outheal and the phase overall is not hard at all. Imo bloodlust is better used on either 3rd or 4th phase.
For phase 3 I suggest kiting. I hunter or ele shaman can very easily kite the biggy and all you need is a priest to dispell when kiter gets stunned. While its defo doable to tank kiting guarantees a smooth phase while tanking them can result on a dead tank since they hit for ~25k on 10man and I would assume ~35k on heroic (havent tried 25man yet). Should be mentioned that they can be slowed by anything (frost shock, earthbind totem, chains of ice, you name it) as well as stunnable. We were just kiting, ranged dps on them, melee on small robots and charge/conc blow or charge/shockwave on every cooldown. Worked like a charm.
I can't comment on phase 4 since we didn't actually kill it
Edit: For phase 3 its possible to have a warrior tank tanking actually. Just open with heroic throw and then spell reflect his 9k (on 10man) hits. Thats some massive threat and since your ranged dps will not be able to go all out (they have to take care of the bots) as long as you spell reflect everytime its on CD you can actually tank it. Not that you have to but its cool nonetheless