Playing as Cain I got, in this order, Polyphemus, Mom's coin purse containing 4 tears up pills, mutant spider, and technology 2. The end result may have been a glitch, but I stopped firing tears when the laser went off. As near as I can tell every time the enemies took damage from the laser they were taking about 4 polyphemus tear worth of it. I got Mom's pad a little after that and using it against all the bosses reduced every fight up to and including Mom's Heart last a matter of seconds.