The Ultimate Boi Afterbirth+ Item Guide

The Binding of Isaac: Afterbirth+ is a game that thrives on its vast and often bewildering array of items. For players diving into the depths of the Basement, understanding the synergies and effects of these items is paramount to survival and eventual victory. Among the most sought-after and impactful are the items associated with the "Boi" family, particularly those introduced or expanded upon in the Afterbirth+ expansion. This guide will delve deep into the world of boi afterbirth plus items, dissecting their mechanics, synergies, and how to best utilize them on your perilous journey.

Understanding the "Boi" Archetype in Isaac

Before we dissect specific items, it's crucial to grasp what the "Boi" archetype represents within The Binding of Isaac's item pool. Often, "Boi" items are associated with Isaac himself, or they grant him abilities that fundamentally alter his combat capabilities, often in ways that are both powerful and visually distinct. These items can range from passive stat boosts to active abilities that can turn the tide of a difficult boss fight. Afterbirth+, with its massive influx of new content, significantly expanded upon this theme, introducing items that interact with existing mechanics in novel ways and offering new strategic avenues for players.

Key Boi Afterbirth+ Items and Their Impact

Let's break down some of the most significant boi afterbirth plus items that players will encounter. Each of these items has the potential to drastically change a run, and understanding their nuances is key to mastering the game.

The Inner Eye

The Inner Eye is a classic Isaac item that received a significant boost in utility and presence with Afterbirth+. This item, visually represented by a large, bloodshot eye, grants Isaac three spectral tears, effectively tripling his tear output. However, it comes with a significant drawback: a reduction in fire rate. This trade-off is a classic Isaac balancing act.

• Mechanics: The Inner Eye provides a massive damage-per-second (DPS) increase, especially when combined with items that boost fire rate or tears. The spectral tears allow Isaac to shoot through obstacles and enemies, adding a layer of tactical advantage.
• Synergies: The Inner Eye synergizes incredibly well with items that increase fire rate, such as Magic Mush or Speed Ball. It also benefits greatly from items that grant additional tears, like The Sad Onion or Cricket's Head. However, be cautious with items that further reduce fire rate, as this can make your tears feel sluggish and difficult to aim.
• Strategic Use: In early game, The Inner Eye can be a run-saver, allowing you to clear rooms with ease. In later stages, its reduced fire rate can be a hindrance against fast-moving enemies or bosses that require precise, rapid shots. Managing your fire rate with other items is crucial to maximizing its potential.

Mutant Spider

Similar to The Inner Eye, Mutant Spider is another item that dramatically increases tear count. Instead of three tears, Mutant Spider grants Isaac four tears, arranged in a wider spread. This comes with an even more significant reduction in fire rate compared to The Inner Eye.

• Mechanics: Four tears mean a massive increase in raw damage output, especially at close range. The wider spread can be both a blessing and a curse, allowing you to hit multiple targets simultaneously but potentially missing single, precise shots.
• Synergies: Mutant Spider pairs exceptionally well with items that increase fire rate, such as The Inner Eye itself (resulting in a devastating seven tears), Tiny Planet, or Mom's Knife. Items that grant homing tears, like Spoon Bender, can mitigate the spread issue.
• Strategic Use: Mutant Spider excels in rooms with many enemies or in boss fights where you can position yourself to hit the boss with multiple tears. However, against single, agile targets, its reduced fire rate and wide spread can be a significant disadvantage. Consider it a high-risk, high-reward item.

Technology Zero

Technology Zero is a unique item that transforms Isaac's tears into a continuous laser beam. This beam pierces through enemies and obstacles, dealing consistent damage. Afterbirth+ introduced new interactions and visual flair to this already powerful item.

• Mechanics: The laser beam has a fixed firing rate, meaning your fire rate stat doesn't directly affect how quickly you can initiate a new beam. However, items that increase shot speed can make the beam travel faster. The laser deals damage over time as long as an enemy is within its path.
• Synergies: Technology Zero synergizes incredibly well with items that grant additional tears or modify tear effects. Brimstone is a classic synergy, creating a wider, more powerful laser. My Reflection can cause the laser to bounce, hitting multiple enemies. Items that grant spectral tears or piercing tears also enhance its effectiveness.
• Strategic Use: Technology Zero is excellent for clearing rooms and dealing with large groups of enemies. Its piercing nature makes it ideal for situations where enemies are lined up. However, its fixed firing rate can be a drawback against bosses that require rapid bursts of damage.

Brimstone

Brimstone is arguably one of the most iconic and powerful items in The Binding of Isaac. It replaces Isaac's tears with a devastating, piercing laser beam that deals massive damage. While not exclusively an Afterbirth+ item, its presence and synergies are amplified by the expansion.

• Mechanics: Brimstone has a charge-up mechanic. The longer you hold the fire button, the longer and more powerful the laser beam becomes. It pierces all enemies and obstacles.
• Synergies: Brimstone has a vast number of powerful synergies. Combining it with The Inner Eye or Mutant Spider results in a wider, multi-beam attack. Technology Zero creates a unique laser that can be angled. Items that increase shot speed or fire rate can also enhance its effectiveness. My Reflection can cause the Brimstone laser to bounce, creating chaotic and damaging patterns.
• Strategic Use: Brimstone is a run-winner. Its raw power allows you to decimate most enemies and bosses with ease. Mastering the charge-up mechanic and positioning is key to maximizing its potential. Be mindful of its charge time, as it can leave you vulnerable if not used strategically.

Mom's Knife

Mom's Knife is another game-changing item that replaces Isaac's tears with a throwable knife. This knife deals significant damage and can be thrown in any direction. Afterbirth+ added new interactions and made it a more accessible item in the pool.

• Mechanics: When you hold the fire button, Isaac charges up the knife. Releasing the button throws the knife. The knife pierces enemies and can be picked up after being thrown. You can also hold the knife in front of you for continuous damage.
• Synergies: Mom's Knife synergizes exceptionally well with items that increase fire rate, as this allows you to throw knives more rapidly. The Inner Eye and Mutant Spider can cause multiple knives to be thrown simultaneously. Items that grant homing tears, like Spoon Bender, can make your thrown knives track enemies. Technology Zero can create a unique effect where the knife is replaced by a laser beam that can be thrown.
• Strategic Use: Mom's Knife offers incredible versatility. You can use it for rapid-fire damage, precise single shots, or even as a defensive barrier by holding it in front of you. Its ability to pierce enemies makes it excellent for clearing crowded rooms.

Synergistic Power: Combining Boi Items

The true magic of The Binding of Isaac, especially with the wealth of boi afterbirth plus items, lies in the synergies between different items. When you start combining these powerful effects, you can create truly game-breaking builds.

The "Quad Shot" Build

Combining The Inner Eye and Mutant Spider is a classic strategy. This results in a seven-tear shot, significantly increasing your damage output. However, the fire rate reduction can be substantial. To counteract this, you'll want to prioritize items that boost fire rate, such as Magic Mush, Speed Ball, or The Sad Onion. This build excels at clearing rooms quickly and dealing massive damage to bosses.

Laser Overload

Pairing Brimstone with Technology Zero creates a unique and powerful laser attack. The laser beam can be angled, and its piercing nature remains. This synergy is particularly effective when combined with items that increase shot speed, allowing the laser to travel further and faster.

Knife Mastery

Mom's Knife becomes even more potent when combined with items that affect tear rate and number. Imagine throwing multiple knives at once, or having your thrown knives home in on targets. Items like The Inner Eye, Mutant Spider, and Spoon Bender can elevate Mom's Knife from a powerful weapon to an unstoppable force.

Navigating the Challenges of Boi Items

While these items are incredibly powerful, they often come with significant drawbacks that players must learn to manage.

• Fire Rate Reduction: Many of the most potent boi afterbirth plus items, such as The Inner Eye and Mutant Spider, drastically reduce your fire rate. This can make dodging and attacking feel sluggish. Prioritizing fire rate-boosting items is essential to mitigate this.
• Spread and Aiming: Items like Mutant Spider have a wide tear spread, which can make hitting single targets difficult. Items that grant homing tears or increase shot speed can help compensate for this.
• Charge Times: Items like Brimstone and Mom's Knife require charge times, leaving you vulnerable during the charge. Learning enemy patterns and positioning yourself correctly is crucial to using these items effectively without taking unnecessary damage.

The Role of Trinkets and Pickups

Don't forget the supporting cast! Trinkets and pickups can significantly enhance the effectiveness of your boi afterbirth plus items.

• Trinkets: Trinkets like Cancer (increases fire rate) or The Tick (chance to shoot tears when hit) can provide valuable buffs.
• Pickups: Consumables like Speed Up pills or Damage Up pills are always beneficial. Certain active items, such as The D6, can allow you to reroll items you don't need, increasing your chances of finding the perfect synergy.

Advanced Strategies and Considerations

As you become more familiar with these items, you can start employing more advanced strategies.

• Room Clearing vs. Boss Fights: Some item combinations are better suited for clearing rooms quickly, while others excel against single, powerful bosses. Understanding the strengths and weaknesses of your current build is key to adapting your playstyle.
• Item Pools: Be aware of the different item pools (Treasure Room, Boss Room, Devil Deal, Angel Room) and which items are more likely to appear in each. This can help you plan your route and anticipate potential synergies.
• The Risk of Over-Synergy: While synergies are powerful, sometimes stacking too many items that reduce fire rate can make your character feel unplayable. It's a delicate balance, and sometimes a slightly less powerful but more consistent build is preferable.

Conclusion: Mastering the Boi Arsenal

The Binding of Isaac: Afterbirth+ offers an unparalleled depth of gameplay, largely due to its intricate item system. The boi afterbirth plus items represent some of the most impactful and transformative additions, capable of turning even the most desperate runs into triumphant victories. By understanding their individual mechanics, mastering their synergies, and learning to mitigate their drawbacks, you can unlock the true potential of Isaac's arsenal. The journey through the Basement is a constant learning process, and with this knowledge, you're better equipped than ever to face its myriad challenges and emerge victorious. Keep experimenting, keep learning, and most importantly, keep shooting.