AST and the new Expert dungeons

[Risvertasashi]

-snip- If your party constantly gets heavy damage then it's not AST's fault, other healers will struggle as well with that kind of party. There's always Lightspeed+Helios+Helios+Helios if somehow needed but personally, up until now, I've been running ex dr as AST and I've never used Lightspeed in that fashion.

As for MP management, well, one thing that I noticed that if you spam Benefic II, you'll run out of MP in no time. So, for me, I'll just use AB, AH (in Diurnal stance) and Benefic I, occasionally Benefic II -snip-

A couple things worth noting.
1. While the bolded is somewhat true, the issue is that AST's threshold for struggling is much lower than the other two. (and, yeah, you're never going to need aoe heal spam in a dungeon).
2. Unlike WHM with Regen, Diurnal AB is actually not MP efficient (generally). Benefic spam is better. You only want to use AB when it lets you avoid casting Benefic II.