AST's buffs

I have 58lvl AST

Confused buffs....
Diurnal Sect and Nocturnal Sect

No idea what best one for dungeon or raid....

I used much Diurnal Sect. Since it's good

It depends on the content you're doing, if you have another healer with you or not (with SCH, always use Diurnal!), and a also on your personal preference. In 4 person dungeons, I prefer Diurnal because I like to have regens running while I DPS, but I'm not a very experienced AST and I also know people can heal those and DPS well in Nocturnal too. :)

As you are leveling, it really doesn't matter which one you use, so long as you are comfortable with it. For instance, since I had leveled a Scholar first, using Nocturnal felt a lot more fluid for me than using Diurnal. While the playstyles don't differ too much from each other, both have some very key things to keep in mind, mostly in just how proactive or reactive you are to healing.

Hey there,

Like Taika mentioned, it boils down to your personal preference. I myself prefer Nocturnal because I like to be proactive instead of reactive. However in 8-man party, it is important to be flexible with this. When your co-healer is WHM, Nocturnal would be preferable (although Diurnal is still okay). When SCH, definitely go Diurnal because our shields overlap with each other. When you have another AST, make sure your sect is the opposite of theirs to maximize the group potential. Also, do be mindful of cardplay in this scenario as cards overlap with each other.

I see that you've already leaning towards Diurnal and that's great, but here are few key points to consider when choosing when to use what:

Diurnal:
Very similar to WHM; you can cast aspected benefic after the tank secured aggro and then you can safely pay more attention to DPS/cardplay. Incredibly effective when there are lots of DoT mechanics around. Generally speaking, this sect allows you to focus more on misc activities other than healing (i.e. DPS, environment interaction, etc.)

Nocturnal:
It's incredibly effective to "stop the bleeding" when tank takes too much damage. Barrier essentially acts as an additional HP that must be depleted first and our shield is quite strong. This would allow you to save the group in tight spots, but require more dedication to party instead of the enemy. Also, it tends to drain more MP compared to Diurnal, but not to a point that you'd be struggling for mana. Still, Nocturnal is great because there would be less surprise and can potentially save someone from enemy burst attack.

No matter what you choose, I hope you'd enjoy AST just as much as we AST mains :D

Pick the mode you like best or feel most comfortable in. I tend to use Nocturnal in a dungeon for trash pulls and Diurnal in the bosses.

In 8-man content, pick the mode that opposes your other healer; Nocturnal with a WHM, Diurnal with a SCH.