Emiya bond CE effect?

So I've been wondering what is the effect of emiya bond ce (the 30% Chance to drop 5 crit star) per hit or per command card since I'm currently in bond level 6 half way to 7 which is good for me and herc with the same bond lvl as emiya since herc bond ce is soo good.

Note: if theirs any grammar error pls forgive me since english is my third language to learn thanks.