I am 5 boxing a tankading + 3 elemental shamans + 1 resto shaman.

For now my resto shaman just sits there casting LHW all the time. Anyways, I was thinking about putting him into better use and let him enter the DPS rotation. The problem is that he tends to run oom much before the elemental guys even get near 75% of their mana pool.

Basically when gryphed + blessing of wisdom + water shield + 4 x mana totems my elemental shamans never run oom even if I am hitting the target dummies during more than 25 minutes nonstop... then I got bored with the elemental guys at near 70% of their mana and thunderstorm unused during all that time.

So my idea was to convert my resto shaman also to elemental and make the following kind of castsequence (simplified for forum purposes)

Shaman 1 --> /castsequence [target=tanks-target] CL, CL, CL, [target=tank] LHW
Shaman 2 --> /castsequence [target=tanks-target] CL, CL, [target=tank] LHW, [target=tanks-target] CL
Shaman 3 --> /castsequence [target=tanks-target] CL, [target=tank] LHW, [target=tanks-target] CL, CL
Shaman 4 --> /castsequence [target=tank] LHW, [target=tanks-target] CL, CL, CL

The idea is that this will overheal the tank because there will be always one shaman casting LHW on him while the others will DPS... and all the shamans will have very similar and predictable mana pool depletion. I have calculated that the overall DPS will be a bit higher than with my current setup because I will be able to put another lava burst into all that rotation combo + another flame shock dot running on the mob all the time.

Also will make my healer shaman a viable toon for PvP rather than a sitting duck complaining that target is out of range or that he is oom.

The problem is... How do I switch the target=tank in the middle of the cast sequence? Is that possible? Has anyone tried a similar rotation before?

So far I have been unable to do that and it's getting me really frustrated.