how many miniature pianus do i need to get hero will?

I read that 1 is not enough, how many i should buy to be sure?
im 130 hero

 

I've tested this myself recently, as a non-mage. I'm a Buccaneer.
Solo
Before the rollback happened, I accumulated about 11 pieces with 1 miniature pianus. I assume you'll need 4 miniature pianus to get hero will.
Party with a NL
I started with 0 pieces, same as the NL. We both used 2 miniature pianus each. On the 4th miniature pianus, we had plenty of extra time.
Conclusion
4 miniature pianus is enough. Party with someone and you'll only need 2.

 

ya 3 or 4 is enough, also selling mini pianuses ch1 fm13 20m ea

 

thanks guys, I done it using 3

 

Took me one for drk and nl, gobies don't track as well as they did in old source though so probably need two at least.