Bind Wendigo’s Mark to it for amazing healing results. If you have some spare gear slots you can use %vitality converted to fire to increase the leech a bit. That celestial power is my go to now for any caster that does not have %weapon damage, like Storm Box of Elgoloth + aether WM. 
It’s a shame that you need to take a vitality based ability to survive. This was all the rage with the Scales devotion but I’m not sure how popular it is anymore.
It’s a glaring thing that most builds needs ADctH to survive Ultimate or seek inferior options for it