I am working on building a deck that primarily uses infect and wither alongside proliferate mechanic to wear down my opponent. I have a work in progress that I have won with once before and an extremely extended list of that deck will be copied below. I am looking for suggestions of what to add more of or get rid of or replace in this deck. any help is greatly appreciated.

2 Inkmoth Nexus
2 Molten Slagheap
6 Mountain
4 Rakdos Carnarium
14 Swamp
2 Scar
1 Tainted Strike
1 Contagion Clasp
2 Crumbling Ashes
1 Iron Myr
1 Leaden Myr
2 Necropede
1 Plague Myr
2 Rustrazor Butcher
2 Stigma Lasher
3 Blowfly Infestation
1 Cinderbones
2 Contagious Nim
1 Corrosive Mentor
2 Grim Affliction
1 Lightning Talons
2 Necroskitter
1 Puncture Blast
2 Razor Swine
3 Volt Charge
2 Whispersilk Cloak
2 Ashenmoor Liege
1 Ashling, the Extinguisher
2 Core Prowler
2 Decimator Web
1 Flesh-Eater Imp
1 Grafted Exoskeleton
3 Hand of the Praetors
1 Slinking Giant
1 Caress of Phyrexia
2 Kulrath Knight
2 Reaper of Sheoldred
1 Skithiryx, the Blight Dragon
1 Spread the Sickness
1 Contagion Engine
3 Dark Withering
1 Grave Titan
1 Phyrexian Juggernaut
1 Rage Reflection

#90
Sideboard:

4 Relic Putrescence

#4

To begin with, what format are you looking to play? Most decks that aren't EDH/Commander run only 60 cards, with a 15-card sideboard.

I play casually, so usually legacy type formats. between 60-70 cards.

Well, I'm seeing a lot of one-ofs in this deck. I might start by trying to reduce those and increasing some multiples.