Utilizing "He Who Fights Monsters"

I have an ideas on to use trhis effectively and I want to know what would be the best case scenario:

1. Say the Hero wants to protect his nakama at all costs, he is generally a good guy but often times makes a ton of mistakes. After a tragedy that befalls his one of his comrades, he makes a deal with a vile character in order to gain a sword to defeat the Big Bad responsible. Although he is warned of the swords effects, he uses to defeat the Big Bad only to fall prey to corruption and become the very person he was fighting.

I wanted to try and think of other scenarios but I am entertaing my cousins now. I am hoping to write a tragic flaw and I am using some references.

Edit: Can anyone get the gist of my thread, I write to fast and I made a ton of spelling errors.

edited 1st Jan '11 7:30:06 PM by G.G.

^You're definitely gonna want to work on that if you want people to understand you. Type slowly, or at least go back and check for errors. I caught three in this post alone, but I fixed them before I posted. It works miracles.

Using He Who Fights Monsters is a bit of an undertaking. Not uses of the trope invoke And Then John Was a Zombie (which seems more like how yours ends) or other nasty ends.

Sometimes the simplest and best use of He Who Fights Monsters is someone who gets carried away by the notions leading to the trope. For example your hero is overly-concerned with protecting his nakama. Getting carried away with that too far can easily fall into the trope especially if the actions fall in line with anything less than universally good.