Astrals

Astros are a good part of you BR and are the gold sink of the game! The tiers are: Green, Blue, Purple, and Orange. As you might think, Purple and Orange are harder to get.

1: Save for Events.
Every now and then there will be an Astro Hot Event where you need to get X many per day for a prize. So I wait on my astros and save gold for these. You can still get 1 per day for Devotion and for bounty quests.But large scale synthesizing of astros is something I wait for Events for.

4. VIP Privilage
The VIP enables the Capture all function of astros which allows you to fill all empty slots in astral inventory in one go. And of course a little more balens/bound balens do help as they can unlock more slots in astral inventory, hence allowing you to synthesize faster.

5. Achievements.
There are achievements for synthesizing astros upto maximum 10000 astros and the final achievement awards you with a special title.

Unlocking slots in astral inventory is also an achievement.