If you're getting bopped when you do that you can always toss shields. It's better than nothing and you're not going to run out of TP anyway. Also if you're getting a Refresh at the start of the fight you can do your Requiescat->FoF, and when FoF is over you'll have enough reserve MP for 3x Holy Spirit and enough gauge to block the tree knockback and the Flare. Those blocks should top you back up to full MP.