This mod is an addon for Enhanced Celestials, and deals with adding special items that summon EC moons.

WIKI:

How to get a blood crystal?

To get this item, you have to kill a zombie (from vanilla Minecraft) and with a 5% chance it will drop.

How to get a lucky crystal?

To obtain this item, you need to break the sculk blocks and with a 0.05% chance it will drop. Don't worry, it's not the smallest chance, if I had set it to ~2% the crystal would drop, literally from every block.

How to get a harvest crystal?

This crystal must be purchased from a level 2 farmer.

How do you get unstable versions of these crystals?