[Gateway103]

Originally posted by Duncanish:
Communion/Sabbath gives +1 in all magic paths, including holy. Crystal shield also boosts holy power, but only in battle.

Just to be clear, Sabbath/Communion increases all magic path levels of associated Masters by X levels, where X = base 2 logrithm of the number of Sabbath/Communion Slaves (rounded down to nearest integer IIRC)

So,
2 slaves give 1 level boost
4 slaves give 2 levels boost
8 slaves give 3 levels boost
so on.

-Gateway103