Originally Posted by
Necessarily
I chuckled at "unwanted"...
PosPos didn't actually answer your question - you should only be casting PoH when you have the single-use buff from Empowered Archangel that gives your next heal 100% critical strike chance, which turns PoH into a 5-man absorb shield with Divine Aegis. What you should be casting otherwise is your level 90 talent (probably Cascade) if raid damage spread justifies it, and blanket Power Word: Shields (possibly with Power Infusion if you need to get a lot of them up fast).