Holy Magic Shell was found to be too broken in more difficult content and needed some fine tuning for balance. Maplers were near completely invincible (excluding HP% based mechanics) facetank all touch damage while the buff duration stacking bishop sat nearby recasting the skill continuously.
The spell is now redesigned to be used more strategically requiring more foresight on the Bishops part to pull off a "Hail Mary" moment.
One other often overlooked JQ is Crimsonwood's Valley of Heroes in Masteria.
If you are able to complete quests from both the Barricade brothers (John and Jack), you will earn ect. items letting you bypass quickly up to Crimsonwood Mountain. The area is great for farming crafting materials Fionna (from the Raven Ninjas) can combine into making some snazzy gear.
Both John and Jack's requests ask that you traverse across the JQ a couple times to complete them. Watch out for those giant spiked rolling pins...