Rabid raccoon bite. She had bleed "Damage over time" effect on her hitpoints, movement makes it worse, Rad waited until Erin's hp was low enough to activate secondary effect: removal of all ingested potions and buffs.
Somebody has forgotten about the limitations of human body...
Also, Et tu, raccoon? Avenge me, Rad. etc, etc :) http://www.escapistmagazine.com/articles/view/comicsandcosplay/comics/erin-dies-alone/15098-Chapter-5-05
Why would a soda bottling corporation have a private army? Easy, because there was someone attacking them. Crystals need private army to conquer the world, it would be easier if all the weapons were close by. So, they made two armies, basically. One to do rebellion, the other to fight against...
My theory: The crystals need humans to ingest them so they can breed. They are indeed crystals of light with plenty of magical powers... but they feed on life force and are really not needed for the world to live. They are more like parasites, actually.
Why would crystal send someone to...
Heroism? Nope. None of that crap. Pragmatic, had to be dragged kicking and screaming to behave even close to heroism, kick-people-in -the-balls-if-it-means-they'll-leave-me-alone ingenuity? Bags of it.
I personally hear this one: http://www.metrolyrics.com/ill-make-a-man-out-of-you-from-mulan-lyrics-various-artists.html
Especially these parts:
"Tranquil as a forest, but on fire within
Once you find your center, you are sure to win"
"With all the strength of a raging fire
That's what happens when you don't level grind and do sidequests, actually. This was obviously final dungeon, Erin was supposed to get new levels, equipment, OP skills and more superleveled characters in the party before even trying it.