It's already very MM intensive to get it to this point, but if I used [Fell Energy] with Sadism (+3 Luck/10 Damage), and actually managed to get it to affect more than 20 targets... it would be quite lovely. Failing that, if I had 20 beefy supplicants to use for this and I were able to pump that damage with features like Smiting Spell (Fiendblooded) that added damage to it without further pushing that adjustment, that could also work!
But chaining it further reduces the damage, so I'll look into modifying the area. So far, it would be a total of +546 (Profane) + 343.2 (Luck) totalling 889. Not quite as impressive as being able to hit 200 targets...