So you're playing The Binding of Isaac: Repentance and you see it. That little "4" next to the item name (if you’re using the External Item Descriptions mod, anyway). Your brain does the happy chemical dance. You think, "Okay, the run is won."
But honestly? Sometimes it’s a trap.
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The system for quality 4 items Isaac introduced in the Repentance expansion changed the way we look at the loot pool. It replaced the old "Special Item" mechanic. Back in the day, taking a Special Item like Brimstone made it harder to find other powerful items. Now, that's gone. Quality is just a label. It's a tag from 0 to 4 that tells the game—and you—how "run-carrying" an item is supposed to be.
But labels can be messy. Some Quality 4s will kill you faster than a champion Muliboom if you aren't careful.
The Mechanics of the "Quality" Tag
Most people think quality is just a tier list. It’s not. It actually drives specific game mechanics. If you're playing as Tainted Lost, the game has a 20% chance to reroll any item that is Quality 2 or lower. This is why you rarely see "trash" on a Tainted Lost run.
Similarly, the Sacred Orb—a Quality 4 item itself—automatically rerolls Quality 0 and 1 items. It even has a 33% chance to reroll Quality 2s.
Then there’s the Bag of Crafting. If you're playing Tainted Cain, the total "quality" of the pickups you toss into the bag determines the quality of the item you get out. You want a Quality 4? You’d better start finding some Eternal Hearts, Golden Pennies, or Lucky Pennies. You can't just shove eight pennies in there and expect Sacred Heart.
The "Run Winners" that Everyone Wants
When we talk about Quality 4 items, we’re talking about the heavy hitters. These are the items that basically play the game for you.
- Sacred Heart: Probably the best item in the game. It’s a massive damage multiplier ($1.5x$), a flat damage up, homing tears, and a full health heal. It’s found in the Angel Room pool. If you see this, you take it. No questions.
- C Section: A relatively new addition in Repentance. Instead of tears, you fire little babies that stay on enemies and deal contact damage based on your DPS. It synergizes with almost everything. Brimstone babies? Yes. Spirit Sword babies? They spin like little fans of death.
- Death Certificate: This is the ultimate "pick your own adventure" item. It takes you to a special area containing every single item in the game. You pick one, and you leave. It’s the rarest item because you have to complete every single hard mode completion mark for every single character to unlock it.
Why Some Quality 4s Are Actually Dangerous
This is where the expertise comes in. Not every Quality 4 is a "press button to win" item.
Take Ipecac. It’s Quality 4 because the damage boost is astronomical. We're talking $+40$ flat damage. But you're firing explosive lobbed shots. If a Leaper jumps into your face while you’re firing, you’re dead. If you have My Reflection? You've just signed a suicide pact.
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Then there's Dr. Fetus. It replaces your tears with bombs. It’s iconic. It’s powerful. It also makes it incredibly easy to corner yourself. Unless you have Pyromaniac or Host Hat (both of which used to be higher quality but have moved around in patches), you're one bad flick of the joystick away from a Game Over screen.
And we have to talk about Abyss and Void. These are active items. Void lets you consume pedestal items to gain stat upgrades or suck up the effects of other active items. Abyss (Tainted Apollyon’s thing) turns them into red locusts that swarm enemies.
Some players hate these. They find them "boring" because you're destroying items instead of using them. But in terms of consistency? Turning a useless Bob’s Brain into a permanent damage-dealing fly is objectively a win.
The "Fake" Quality 4s and Hidden Gems
The community debates this constantly. Some items feel like they belong in Quality 4 but are stuck in Quality 3.
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- Rock Bottom: This is a Quality 3 item that many people think should be a 4. It makes it so your stats can never decrease. If you use a Strength card, the damage boost stays forever. If you pick up Soy Milk after Polyphemus, you keep the huge damage but get the insane fire rate. It's break-the-game tier.
- Spoon Bender: Just Quality 3. But homing is one of the most powerful effects in the game.
- Stopwatch: This is Quality 4, and it's one of the few found in the Shop pool. It slows down all enemies and projectiles in every room. It’s arguably the best defensive item in the game, yet people often pass it up because they want to save money for Champion Belt or Diplopia. Don’t be that guy. Buy the watch.
What changed in the 1.7.9 patch?
Edmund McMillen and the team at Nicalis aren't afraid to move the goalposts. In the 1.7.9 patch, they did a massive sweep.
Serpent's Kiss used to be a Quality 4. Why? Because it used to drop Black Hearts on contact damage. They nerfed that—now it only drops them on poison kills from the "virus" effect—so they dropped it to Quality 2.
Psy Fly also got moved. It used to be Quality 4 because it was basically an automated "you can't be hit by bullets" machine. They added a cooldown to its reflecting ability. It's still amazing, but it’s no longer the undisputed king of defense.
Actionable Tips for Your Next Run
Don't just look at the number. Context is everything in Isaac.
- Check your synergies before taking Dr. Fetus or Ipecac. If you have high shot speed and Rubber Cement, you are going to hit yourself. It is a mathematical certainty.
- Prioritize the Secret Room. Items like R Key and Death Certificate live here. If you find a Spindown Dice (Quality 4), you can "spin down" certain items into these god-tier rewards. For example, Bot Fly spins down into Death Certificate.
- Don't ignore the Shop. Since most Quality 4s are in the Treasure, Angel, or Devil pools, the Shop feels weak. But Stopwatch is right there. If you see it, and you have 15 cents, you buy it. It makes bosses like Delirium and The Beast significantly more manageable.
- Understand the Sacred Orb. If you find this early, do not take "okay" items. Reroll them. The Orb is designed to force the game to give you the top 10% of the item pool.
Quality 4 items aren't just about power. They're about how much they change the rules of the game. Brimstone changes your attack. Holy Mantle changes your health logic. R Key literally restarts the clock.
Mastering Isaac isn't about finding these items—it's about knowing which ones will actually save your run and which ones are just a flashy way to blow yourself up.