I myself always make sure to pop largesse after eating my fairy which grants just enough shield pot. to let me cast another spell before the tank starts falling again.

Things I'm aware of:

- AF unaffected by pot. boost
- Mp cost of succor and Adlo (Your shielding spells which are affected by Pot. boost) are still very much expensive.
- The skill clashes with Fey Union (Which I still haven't bothered to retrieve yet, give me reasons why and I might.)