It's been a little while. After beating tomb level 4 boss, you found out you need to acquire something to get pass that part. Just progress with the story and you will eventually pick that up.
Thanks, I'll progress the story then.
As for the HP regen, it is by design so you don't whack at bosses mindlessly. Just make strategic use of your TP attacks and take advantage of elemental weakness. 2 back to back TP attack from Jiao usually floor the boss, except the very last boss.
Yeah, noticed. But for those bosses where you don't have her it would be a godsend cuz other characters miss attacks/skills quite a bit. And it would be fun to have it used against you. I rarely have to heal since equipment with HP regen is abundant.