Hmmm, not sure this will help, but first tip, do it with lv60+ cleric. Instant heal.
If not 60, then never let prevention or life cure disappear.
Prevention leveled enough should reduce over 120 of taken damage wich is pretty much all the spawnlings should do?
I did it 1p with 60 cleric and didn't get any trouble with it. Just tornado-sanction's light-earth shock and repeat that over and over, healing inbetween if necessary. Tornado takes out all of the spawnlings and also when you hit them it procs cast speed stuff wich is cool for insta-cast heals/earth shock.