Hello there before getting our madness of deathwing heroic kill we had quite a few problems with tanks surviving during the impales which does around 1.2 million dmg and can not be reduced thro armor. So basicly after our kill i wanted to share the CD rotaions for each platform to my fellow tanks. Get the hyjal trinket its the most powerfull one for that fight the otherone is optional, Have a disc priest if you run 25 man guild like we do run even 2 thier big shileds are really great just make sure to tell your priests to apply the PW:S just when the corruption is about to cast impale.
Ysera
platform 1, impale 1: Dream + B-Shield + PW:S + Sac + VB + (Hyjal trinket 20% reduc dmg)
platform 1, impale 2: dream + divine protection + trinket (Hyjal trinket 20% reduc dmg) + sac
Alextraza
platform 2, impale 1: IBF + B-Shield + PW:S + Sac + VB + (Hyjal trinket 20% reduc dmg)
platform 2, impale 2: PS + divine protection + trinket (Hyjal trinket 20% reduc dmg) + sac
Nozdormu
platform 3, impale 1: PS + B-Shield + PW:S + HoSac + VB + trinket(Hyjal trinket 20% reduc dmg)
platform 3, impale 2: GOAK + devine protection + trinket (Hyjal trinket 20% reduc dmg) + sac
Kalecgos
platform 4, impale 1: IBF + B-Shield + PW:S + HoSac + VP + trinket(Hyjal trinket 20% reduc dmg)
platform 4, impale 2: PS + devine prot + ardent defender + sac + trinket(Hyjal trinket 20% reduc dmg)
platform4, impale 3: dancing rune + army + B- shield + sac + VB + PS + trinket (Hyjal trinket 20% reduc dmg)
The cd rotaion above are meant to be for pala and dk tanks but just change the similar dmg reduc cds to warr or druid it will work with no problem but make sure u give sac on everyplatform and the guy who sacs you needs to use devine prot unglyphed her/himslef the dmg is big. We some tiems got third impale on last platform and sometimes not but we made cds for third aswell incase the dps will be too low to kill the corruption in time.
I hope this helped and gl getting your kill