Looks like it takes some half of the year to either collect the required
amount of blasts or to gather enough motivation to really concentrate on
increasing the purity:
You are done with the chant.
You swing your crucifix of St. Kaaymeth and humbly utter 'Sanctum circum'
(holy bolt) 
Surges of holy force coil around your crucifix of St. Kaaymeth forming a
pulsing bolt of divine energy. You twist your wrist and bolt hurls through the
air bursting on Zombie-cop.

You feel more pure and closer to Las.
At 85% now.