Common items, all of them.

Armor-Piercing Rounds

You do 20% more damage to bosses. Each extra one adds 20%.

Stacking: Each copy adds the same, no cap.

Watch out: Only works on enemies with a red health bar (bosses).

Needs unlocking first (challenge «Advancement»).

Backup Magazine

Your secondary skill (right click) gets one more use before its cooldown. Each extra magazine, one more.

Stacking: Each copy adds the same, no cap.

Watch out: More uses, but it does not lower the secondary cooldown. Lets Engineer place more mines.

Needs unlocking first (challenge «Flawless»).

Bison Steak

You get 25 more health. Each extra steak adds 25.

Stacking: Each copy adds the same, no cap.

Watch out: It is added before percent-health items. With one Shaped Glass, each steak gives half.

Bundle of Fireworks

Every time you open a chest or use something in the stage, 8 fireworks fly at enemies. Each extra bundle adds 4.

Stacking: Each copy adds the same, no cap.

Watch out: If the crit roll succeeds, every rocket in that batch crits.

Needs unlocking first (challenge «...Maybe One More.»).

Bustling Fungus

Stand still for a second and a circle appears that heals you and allies inside. Each extra fungus makes it bigger and heal more.

Stacking: Each copy adds the same, no cap.

Watch out: It heals based on the health of whoever is inside, turrets and drones too. Some skills push you slightly and break the circle.

Cautious Slug

When you are out of combat, you heal faster (+3 health per second). Each extra slug adds 3 more.

Stacking: Each copy adds the same, no cap.

Watch out: What matters is not taking damage, not stopping your attacks (the game says «out of combat», which is wrong).

Chronic Expansion

Each kill gives you 3.5% more damage for 7 s, up to 10 times; it lasts as long as you keep hitting. Each extra one raises the cap.

Stacking: Each copy raises damage per kill a little (+1%) and the cap by 5 more kills.

Watch out: Go 7 s without dealing damage and you lose it all.

Crowbar

You do 75% more damage to enemies that still have almost full health (over 90%), so your first hit lands much harder. Each extra crowbar adds another 75%.

Stacking: No cap: each crowbar adds another 75%. With two, the first hit already beats a critical hit.

Watch out: Only the hit that lands while the enemy is above 90% counts; missiles and lightning from other items do not get it. In a group, if an ally hits first, you lose it.

Needs unlocking first (challenge «The Basics»).

Delicate Watch

You do 20% more damage, but it breaks if you drop below 25% health. Each extra watch adds 20%.

Stacking: Each copy adds the same, no cap.

Watch out: The 25% counts health plus shield. Unstable Transmitter and Power Elixir trigger before the watch breaks.

Eclipse Lite

When a skill comes off cooldown, you get a layer of temporary health. The longer its cooldown, the bigger the layer. Each extra one, bigger.

Stacking: Each copy adds the same, no cap.

Watch out: Nearly useless with Transcendence (your health is 1). It takes about 11 to outpace barrier decay.

Energy Drink

You sprint 25% faster. Each extra drink adds 25%.

Stacking: Each copy adds the same, no cap.

Watch out: Only while sprinting. Best on survivors who attack while sprinting: Mercenary, Huntress, False Son.

Focus Crystal

You do 20% more damage to enemies close to you (within 13 m). Each extra crystal adds 20%.

Stacking: Each copy adds the same, no cap.

Watch out: It also boosts burn and bleed damage on nearby enemies.

Gasoline

When you kill an enemy, the ones around it catch fire. Each extra gasoline makes the fire bigger and stronger.

Stacking: Each copy makes the fire bigger and last longer; the burst itself does not get stronger.

Hiker's Boots

Hitting from above the enemy gives you more critical chance and critical damage, up to 10 times. Each extra pair adds more each time.

Stacking: More boots give more per hit, but 10 hits from above always fill it.

Watch out: Your feet only need to reach about the enemy's mid-body.

Lens-Maker's Glasses

10% of your hits are critical and do double damage. Each extra pair adds 10%; with ten, every hit is a crit.

Stacking: Capped at 10: with ten, every hit crits. The eleventh does nothing, unless you plan to turn them into Lost Seer's Lenses.

Watch out: On Railgunner they give no crits: each pair adds 10% crit damage instead. Crit chance does not depend on the hit's proc coefficient.

Medkit

Two seconds after taking a hit, you heal 20 plus 5% of your health. Each extra medkit heals another 5%.

Stacking: Each copy adds the same, no cap.

Watch out: If you get hit again within 2 seconds, the wait starts over: weak if you are hit constantly.

Needs unlocking first (challenge «Elite Slayer»).

Mocha

You attack 7.5% faster and move 7% faster. Each extra coffee adds the same.

Stacking: Each copy adds the same, no cap.

Watch out: Exactly half a Syringe plus half a Goat Hoof.

Monster Tooth

Every enemy you kill drops a little orb that heals you (8 health plus 2% of your max). Each extra tooth heals another 2%.

Stacking: Each copy adds the same, no cap.

Watch out: You have to get close to pick the orb up: much better on melee survivors.

Oddly-shaped Opal

While you are not being hit, you have a lot more armour (the first hit does much less). Each extra opal adds the same.

Stacking: Each copy adds the same, no cap.

Watch out: A blocked hit (Tougher Times) does not remove it; Shrines of Blood or REX skills that cost health do.

Paul's Goat Hoof

You move 14% faster. Moving fast means dodging better. Each extra hoof adds 14%.

Stacking: Each copy adds the same, no cap.

Watch out: Always on. While sprinting, Energy Drink is faster (25% versus about 20%).

Needs unlocking first (challenge «"Is This Bugged?"»).

Personal Shield Generator

Gives you a blue shield worth 8% of your health that refills when you stop getting hit. Each extra one adds 8%.

Stacking: Each copy adds the same, no cap.

Watch out: The shield only comes back after 7 s without damage. Shaped Glass shrinks it. With two or more, your protection against one-shots relies on the shield.

Power Elixir

If you drop below 25% health, you drink it and heal 75%. It is used up.

Stacking: One is used up each time it triggers.

Watch out: Paying the second or third offering at a Shrine of Blood uses it up.

Repulsion Armor Plate

Every hit you take does 5 less. Great against lots of small hits. Each extra plate takes off 5 more.

Stacking: Each plate takes 5 more off every hit, no cap; a hit never goes below 1.

Watch out: Shines against lots of small hits and burns.

Roll of Pennies

You get a little gold every time you take damage. Each extra roll, more gold.

Stacking: Each copy adds the same, no cap.

Watch out: Self-damage and fall damage give no gold.

Rusted Key

Each stage, a hidden box with an item appears; opening it uses up one key. More keys, better items.

Stacking: More keys do not spawn more boxes: the number of boxes depends on how many players hold a key.

Watch out: The box starts appearing the stage after you pick up the key. In a group, spread the keys.

Needs unlocking first (challenge «Keyed Up»).

Soldier's Syringe

You attack 15% faster: more shots and hits per second. Each extra syringe adds another 15%.

Stacking: Each copy adds the same, no cap.

Watch out: Only speeds up attacks and animations: it does not lower skill cooldowns. Bandit does not shoot faster, he only reloads faster.

Sticky Bomb

5% of your hits stick a bomb to the enemy that explodes shortly after. Each extra bomb adds 5%.

Stacking: Each copy adds the same, no cap.

Watch out: With full-proc attacks, one bomb averages about 9% more damage.

Stun Grenade

5% of your hits stun the enemy for 2 seconds. Each extra grenade adds 5%.

Stacking: Each copy adds less than the last: it never reaches 100%.

Watch out: The chance drops with attacks that have a low proc coefficient.

Topaz Brooch

Every kill gives you a layer of temporary health (15) that wears off. Each extra brooch adds 15.

Stacking: Each copy adds the same, no cap.

Watch out: The barrier decays on its own (3.33% of your health per second) and the brooch gives a fixed amount: with high health it falls off, and Aegis beats it once you heal well.

Tougher Times

Sometimes a hit that would land does nothing: with one bear, 13% of hits. More bears raise the chance, but less each time: it never reaches 100%.

Stacking: Each bear adds less: one blocks 13% (not the 15% the game says) and ten block 60%. It never reaches 100%.

Watch out: Luck (Clover) does not affect it. A blocked hit does not trigger enemy effects either, like Overloading Elite bombs. It does not stop Void Reaver implosions.

Needs unlocking first (challenge «Learning Process»).

Tri-Tip Dagger

10% of your hits make the enemy bleed, losing health for a few seconds. Each extra dagger adds 10% chance.

Stacking: Each dagger adds the same: with ten, every hit that counts in full bleeds.

Watch out: It shares its chance with Noxious Thorn (they do not roll separately), and with Shatterspleen only one bleed lands per hit. Attacks with low proc put shorter bleeds.

Warbanner

When you level up or start the teleporter, you plant a banner: you and nearby allies attack and move 30% faster. Each extra banner makes the area bigger.

Stacking: The radius grows the same each time, so the area grows more and more. In a group, better to stack them on one player.

Watch out: Engineer turrets do not inherit it, but they make good use of the banner since they never move.

Warped Echo

The next hit you take is split into 3 smaller hits and does 10% less. Recharges every 15 s. Each extra echo splits it into one more hit.

Stacking: Each copy splits the hit into one more part (3, 4, 5...).

Watch out: The echoed parts cannot kill you, except the last one.