I'm not near my rule books, but I'm pretty sure I saw it referenced as a complex action. But possibly I just assumed that since melee combat was complex, astral combat would be too?
And out of curiosity, what are you doing to get a DV that high?
In my game the shaman has also found that astral combat is often the way to go, but is more inclined to send his spirit (in astral form) after opposing spirits. The opposing spirit will be at an initiative disadvantage unless it also goes astral, which can buy time for the team to do whatever they need to do. He's tended to avoid astral combat after discovering how deadly it is due to lack of armor.