This is untested, as I'm at work. But lets see if this works:

/cast [target="Torrla-target",nodead,exists] [target="Thorra-target",nodead,exists] [target="Torrma-target",nodead,exists] [target="Torrba-target",nodead,exists] [] Lightning Bolt

/follow [target=Torrla,nodead,exists] [target=Thorra,nodead,exists] [target=Torrma,nodead,exists] [target=Torrba,nodead,exists]; Party1