Dump of info from spreadsheet:
Shielding Rune 2 Defense Can stack. Can be found at start of game, Soul Coin Merchants, or Astronauts.
Power Ring 10 Attack Can stack. Can be found at start of game, Soul Coin Merchants, or Astronauts.
Blooddrinker's Ring Drinking a potion gives +5 Attack Can stack. Can be found at start of game, Soul Coin Merchants, or Astronauts.
Defense Damage Every 3 defense gives 1 attack (More def = more dmg) Can stack. Can be found at start of game, Soul Coin Merchants, or Astronauts.
Death's Blessing Lower health raises your attack Can stack. Can be found at start of game, Soul Coin Merchants, or Astronauts.
Chaos Dice Improved Crit Chance Can stack. Can be found at start of game, Soul Coin Merchants, or Astronauts.
Ceremonial Axe Using an axe gives +5 Attack Can stack. Can be found at start of game, Soul Coin Merchants, or Astronauts.
"Vitality Snare " 5% Lifesteal Can stack. Can be found at start of game, Soul Coin Merchants, or Astronauts.
Car Door 10 Blood Resist Living Armor Exclusive?
Flameproof Armor 5 Fire Resist Fight exclusive.
Body Armor 5 Blood Resist Fight exclusive.
Reinforced Armor 5 Physical Resist Fight exclusive.
Zap Armor 5 Zap Resist Event exclusive.
Metal Mask 7 Witch starting item. Fight Exclusive.
Goggles 0 Adds 4 Attack Chef starting item. Fight exclusive.
Tough Guy Helmet 3 Adds 1 Attack Fight exclusive.
Spiked Boots 1 Adds 4 Attack Event exclusive.
Respirator 1 Nuke Resist