Very complete and helpfull guide.
Maybe it just misses a warning about Guardian Spirit as a CD for solo static shocks : Guardian spirit heals you for 50% of your life if damage kills you. However, it does take into account overkill damage, meaning if static shock does more than 150% of your life (or you're not at full health), you are actually dead. I play barely only disc now but i used to go holy for this fight in normal mode the first times just to get the Hymn in phase 3. I strongly advise to use a self or external CD or a little damage reduce and/or active healing (a Power word: Shield + Prayer of Mending works fine most of the time in normal, but you would need a real defensive cooldown in HM). A precasted greater heal should also be needed depending on the defensive cooldown used to avoid dying from adds, Diffusion chain or Helm of Command.
Assuming you have 550k hp pool (that's a more than decent one actually for a first kill), the skill itself can deal with about 750k damage (you die with 775), an if i'm right, the skill does about 1M, even at lvl 1 in hard mode, so forget about Guardian Spirit unless you pair it with a strong (30% or more) damage reduction cooldown. The only exception i can see is a warlock with Dark bargain, as the spell synergise well with DoT damages (you can even underheal the warlock and let him die in the last second of the DoT so he'd be "freely" healed for 50%hp).