[Catharsis]

I assume an Amalgama's overall ability changes depending on the amount of souls used, but from the sound of things, there also has to be a point where the number of souls is either too few for it to help much, or instead too many to be able to reliably stitch together. So, what is the upper and lower limit on the number of souls that can be used to create an Amalgama, and what are the exact results of going under or over those limits?