Body Modifiers reside in the softer mechanics of the quest.
Depending on how a certain blow lands, and how much damage it does, direct effects can be applied to the opponent.
Using a Hell Beast as an example:
Lets say you shoot a motherfucker in the face with your Purifier Beam.
(Purifier Beam: 5,725 Base Damage, +364 Dice, +2,862 Supremacy, +500 Hostile Divinity Effect = 9,451 Total Damage
Hell Beast: 200 Base Resilience, -19 Dice, -150 Juggernaut = 31 Damage Reduction
9,420 Total End Damage
Hell Beast Health: 20,000 - 9,420 = 10,580 Remaining)
You take damn near half it's health in a casual backhand. Now, at this point the Purifier Beam is firing off blasts that can accidentally a skyscraper (and more) if Nepgear isn't holding back. So this Hell Beast just got hit by a beam that could probably envelope it whole when taking this damage. And considering it's a purification effect, it probably burns like a mother fucker.
Now, at this point I'd take into account that Hell Beasts are roughly the size of a large troop transport like the Skybound, and what their weakest limbs are that are most likely to break when hit by something like that.
This specific Beast, I would say had one of it's wings blown clean off, and is heavily dazed from both A) taking a Purifier Beam to the face and B) falling out of the sky rather suddenly.
The missing Wing meands it can no longer fly, and the Daze means he's stunned and is suffering a -20% power malus. And if I'm feeling really vindictive I can also say the poor fucker landed in front of one of the Messengers.
"Roadkill" is a very vexing state of existence for such a large being.