There’s an idea that has been sitting on my mind for quite some time, I’ve been calling it The Scorpion. He’s a boss that you would fight like a Tank.
Basically, he’s a bottomless torso that uses his arms to crawl around. (If you’re someones who’s ever played DeadSpace, The Leaper is a pretty good idea of what I’m talking about). His arms have become rather bulky from having to always carry himself (NOT tank sized), and his legs/lower body are completely gone. His lower half tappers off around his spine, which has now been filed to more of a point. There is still a good deal of muscle around this spine(now tail), giving him enough control to be able to curl it and whip it around.
His mutation would actually be a powerful, mildly acidic toxin that he creates, most likely somewhere in the end of his spinal chord (possibly what paralyzed his lower half before eroding it away). This toxin is what actually makes him a real threat. And as many of you can guess, he delivers it be stinging you with the end of his (now tail) spine.
Once stung with with this toxin, you would begin to feel withdrawal; you become slower, you begin to stagger, your aim begins to wobble, and to top it all off your permanent health slowly converts into temporary as it bleeds out. The duration of this would vary by difficulty, but would last indefinitely on Expert of Realism (meaning it will kill you if it isn’t taken care of).
There would be 2 (or 3) ways to cure yourself. 1st be to simply heal, this would take a sec to stop the symptoms, but it would prevent all of your bleeding out. 2nd would be using an Adrenaline Shot (being one of its real life implications), this would immediately stop all symptoms (but give no additional speed boost). 3rd would simply be patience (if you really call that a cure), as on any normal difficulty the effects would die down after a brief period (and in the case of Expert or Realism, getting it to the next chapter would also make the effect go away).
His main difference in combat is that, unlike the way a Tank fights, he would be quick and sneaky, scurrying in and stinging you, before scrambling away to recharge. As such, battling him would be a bit more suspenseful (With fitting music, like in Jaws), since you would need to stay on your toes, taking special care for any teammates that gotten stung.