A never before seen historical vendetta" - cut this out. Although this particular story has never been told, western vendetta stories are as old as the hills. Plus, it's taking up valuable character space.
"inside the walls of the elegant white elephant gambling hall and infamous brothel" - is this a contained action/thriller? If not, leave out.
"where heaven and hell merge" - cliche and meaningless, plus muddies up the genre. Is this a metaphorical or literal statement? Is this a supernatural western? Is this your hook?
You're being really vague and coy about your story - all I know so far is these two characters are going to clash but I don't know why. If you don't tell us why, it's hard for us to be interested.
This isn't your story but here's what I mean:
To avenge the death of his wife, a professional gambler tracks her killer, a corrupt US Marshall, to the dusty town of [insert name] and wages a war that takes the townsfolk by storm.
You?ve got:
Protag = gambler
Antag = US Marshall
Goal = avenge his wife?s death
Stakes = guilt/remorse
Still missing a hook though - what makes this unique/different from other western revenge stories?