Board Thread:False Info and Speculative Discussion/@comment-4723271-20170918140954/@comment-4091815-20170921035021

One of the very first things we learned about the supernaturals was that if the weapon, be it arrow or bullet, remained in the body - they cannot heal.

Allison learned this in Season one.

Derek referenced it to Boyd after their showdown with the hunters at the Rave.

You have to get it out or you don't heal.

Poisons a re effective because, no matter how much the body tries to heal, the poison remains inside them. We've seen this with  purple Wolfsbane which almost killed Derek in Magic Bullet and Silver, which is apparently something lethal to Oni and Hellhounds, and the distemper virus cooked up by the chemist which took out most of a pack and almost killed Scott, Malia, and Kira.

We knew almost nothing about hellhounds before this (except you can't blow them up) the fact that some people thought they couldn't be killed doesn't mean those people were right. They were tough, but this was the right weapon at the right moment at point blank range. If it had not been sheathed in silver, Halwyn would have been fine once they got it out.

For folks saying this is somehow inconsistent, we've seen over and over again that everything can be killed. The beast couldn't be killed until it was. The dreads seemed unkillable until they were. Ghost Riders were immune to almost everything except their own weapons which did the trick. Nogitsune - just transform it. Oni - Silver. Berserker - crush its head. Everything on this show can be killed.