The Lucky Block Mod can get different 'luck levels' if you put them in a crafting table with certain items.
The 'Luck' of a lucky block is diplayed as a bar from 0 to 100.
The higher the luck level, the more likely it is the lucky block will give you something good.
Luck levels can also be negative, 0 to -100. Negative luck levels make lucky blocks unlucky.
Only Lucky Blocks with a luck level of 0 can be stacked.
Download Lucky Block 1.7.10