Warhammer 40,000: Inquisitor - Martyr

This should come naturally when going for the 100 Embodied Saint uses, but you'll want to have the Sacred Rite you start with as I found that one the best for generating Faith in order to use Embodied Saint form. The ability gives you constant faith regen at a rate of 0.01% per enemy killed, meaning the more enemies killed the faster it fills up.

Once your faith meter is filled, press L3 and then go to town taking down mobs. I found the default A attack in Saint form was the most effective.