If you see spam healing coming, use Rouse + Fey Illumination + Whispering Dawn. Even on single target it's HPS gain. Ofc wait for tank to have enmity and be sure Eos is in range.
If your mana allows it use Adlo every 1 or 2 Physics. If you don't overwrite shield, it's de facto 600 potency heal that goes to 900 on crit.
Don't just spam Lustrate. Make sure you don't overheal with it.

If it makes you feel better, at 70 SCH is (imho) the best healer for such situations thanks to Fey Union and Excogitation.