Unlocking All Completion Marks in The Binding of Isaac: A Comprehensive Guide

The Binding of Isaac is a roguelike dungeon crawler known for its immense replayability and challenging gameplay. A significant part of the game revolves around unlocking various items, characters, and challenges by achieving specific milestones. One of the most rewarding aspects is earning all completion marks for each character. These marks signify that you have successfully completed all major challenges with that character, and unlocking them all is a badge of honor for any dedicated player. This guide provides a comprehensive roadmap to obtaining all completion marks in The Binding of Isaac, covering strategies, tips, and considerations for each character and boss.

Understanding Completion Marks

Completion marks are visual indicators on the character selection screen that show which major bosses you have defeated with a specific character. There are several key bosses and challenges you need to overcome to earn these marks:

• Mom: Defeating Mom unlocks further challenges.
• Mom’s Heart/It Lives: Defeating Mom’s Heart ten times unlocks It Lives, a more challenging version.
• Isaac: Defeating Isaac is essential for unlocking the Cathedral path.
• Satan: Defeating Satan unlocks the Sheol path.
• The Lamb: Defeating The Lamb requires defeating Satan first and using the Negative Polaroid.
• Blue Baby (??): Defeating Blue Baby requires defeating Isaac first and using the Polaroid.
• Hush: Defeating Hush is a significant challenge and requires reaching it after defeating Mom in under 30 minutes.
• Mega Satan: Defeating Mega Satan requires finding the Dad’s Key or using specific items to open the door in the Chest or Dark Room.
• Delirium: Defeating Delirium is one of the ultimate challenges, unlocked by defeating Hush or through other means like Void portals.
• Mother: Defeating Mother requires going through the Corpse path, accessed by using the Knife Pieces obtained in Downpour and Mines.
• The Beast: Defeating The Beast requires completing the ascent path, accessed by using the Red Key or Cracked Key on the Home floor.

Earning all these completion marks for each character not only unlocks new items and content but also demonstrates mastery over the game. [See also: Character Unlock Guide]

Strategies for Earning Completion Marks

Each character in The Binding of Isaac has unique starting stats and items, which can significantly impact your approach to earning completion marks. Here are some general strategies and character-specific tips:

General Tips

• Prioritize Survivability: Focus on items that increase your health, defense, or healing capabilities. The more health you have, the better your chances of surviving difficult encounters.
• Learn Enemy Patterns: Understanding how enemies move and attack is crucial for dodging and avoiding damage.
• Utilize Devil and Angel Deals: These deals can provide powerful items that can significantly boost your run. Weigh the pros and cons of taking a Devil Deal (which costs health) versus an Angel Deal (which requires skipping Devil Deals).
• Practice Makes Perfect: The more you play, the better you will become at recognizing item synergies and making strategic decisions.
• Understand Item Synergies: Some items work exceptionally well together. Learning these synergies can turn a mediocre run into a winning one.

Character-Specific Strategies

Isaac

Isaac is the default character and is well-rounded, making him a good starting point. His main advantage is the D6, unlocked by defeating Isaac as ??? (Blue Baby). The D6 allows you to reroll items, giving you more control over your build. Focus on finding powerful items and rerolling less desirable ones. Earning all completion marks with Isaac is a great way to learn the fundamentals.

Magdalene

Magdalene starts with the Yum Heart, which provides a small amount of healing. This makes her more forgiving in the early game. Focus on building a strong offense to complement her survivability. Prioritize health-boosting items and defensive synergies.

Cain

Cain starts with a key and the Luck Foot, which increases your luck stat. This makes him more likely to find better items and have favorable outcomes in certain events. Utilize his luck to find powerful items and exploit item synergies. He is generally considered one of the easier characters to earn completion marks with.

Judas

Judas starts with high damage but only one heart container. This makes him a high-risk, high-reward character. Play aggressively and focus on dealing as much damage as possible to defeat enemies quickly. Avoid taking unnecessary risks and prioritize items that increase your damage output. Earning all completion marks with Judas can be challenging but rewarding.

?? (Blue Baby)

Blue Baby starts with three soul hearts but cannot gain red heart containers. This makes him reliant on soul hearts and black hearts for survival. Focus on finding items that generate soul hearts or black hearts, such as the Book of Revelations or the Rosary. Play cautiously and avoid taking damage whenever possible. Defeating Delirium with Blue Baby is particularly challenging.

Eve

Eve starts with the Whore of Babylon and the Dead Bird. The Whore of Babylon activates when Eve has one or fewer heart containers, increasing her damage and speed. The Dead Bird attacks enemies when Eve takes damage. Utilize this combination to deal significant damage and clear rooms quickly. Prioritize items that synergize with the Whore of Babylon, such as items that remove heart containers.

Samson

Samson gains damage as he takes damage, making him a powerful character in prolonged fights. Focus on maintaining a balance between dealing damage and avoiding excessive damage. Items that provide health regeneration or temporary invincibility can be particularly useful. Understanding how to maximize his damage output is key to earning all completion marks.

Azazel

Azazel starts with a powerful short-range brimstone attack and the ability to fly. This makes him one of the strongest characters in the early game. Use his brimstone to quickly clear rooms and defeat bosses. However, his short range can be a disadvantage in some situations, so prioritize items that increase his range or provide additional defensive capabilities. Azazel is often considered one of the easiest characters to earn all completion marks with.

Lazarus

Lazarus starts with a pill and can revive once with an increased damage stat. Use his revival strategically to overcome difficult encounters. Prioritize items that improve his overall stats and compensate for his lack of starting advantages. Playing aggressively after reviving can help secure victories.

Eden

Eden starts with random stats and items, making each run unique. Adapt your strategy to the items and stats you start with. This character requires a flexible playstyle and a good understanding of item synergies. Earning all completion marks with Eden can be unpredictable but rewarding.

The Lost

The Lost starts with no health and can only be hit once. However, he can fly and starts with the Holy Mantle, which provides one free hit per room. Play cautiously and prioritize items that provide additional defensive capabilities, such as the Holy Card or the Dead Cat. Utilizing Devil Deals is often a good strategy, as The Lost does not need to worry about losing health. Defeating Mega Satan and Delirium with The Lost are particularly challenging achievements.

Lilith

Lilith starts with the Incubus familiar, which duplicates her attacks. This makes her a powerful character for dealing damage. Focus on items that synergize with familiars, such as the Box of Friends or the BFFS! item. Managing her familiars effectively is key to earning all completion marks.

Keeper

The Keeper starts with only two coin hearts and cannot gain red heart containers. He also has a high chance of being able to purchase items with pennies. Focus on generating coins and utilizing shop items to your advantage. Items that provide additional coin hearts or defensive capabilities are crucial for survival. The keeper is one of the most challenging characters to earn all completion marks with.

Apollyon

Apollyon starts with the Void, which allows him to consume items and gain stat boosts. Use the Void strategically to improve your stats and create a powerful build. Prioritize items that provide significant stat boosts or have useful effects when consumed by the Void. Apollyon’s ability to adapt makes him a versatile character for earning completion marks.

The Forgotten

The Forgotten starts with a bone club and a soul. The bone club is a melee weapon, while the soul can be used to swap between the Forgotten and his soul form. Utilize both forms effectively to deal damage and avoid damage. Items that synergize with melee weapons or provide defensive capabilities are particularly useful. Mastering the Forgotten’s unique playstyle is key to earning all completion marks.

Bethany

Bethany starts with the Book of Virtues, which generates wisps when she collects soul hearts. These wisps provide various benefits, such as dealing damage or providing defensive capabilities. Focus on generating soul hearts and utilizing the wisps to your advantage. Items that synergize with soul hearts or provide additional benefits for Bethany are crucial for survival.

Jacob and Esau

Jacob and Esau start as two separate characters that must be controlled simultaneously. This makes them a challenging character to play, as you must manage the positioning and stats of both characters. Focus on building a balanced build for both characters and utilizing their strengths to your advantage. Items that provide benefits to both characters are particularly useful. Defeating Mother with Jacob and Esau is one of the most difficult challenges in the game.

Boss-Specific Strategies

Each boss in The Binding of Isaac requires a different strategy. Here are some tips for defeating the major bosses:

• Mom: Stay mobile and avoid her attacks. Focus on dealing consistent damage.
• Mom’s Heart/It Lives: Prioritize destroying the hearts that spawn around the room. Avoid getting trapped in corners.
• Isaac: Learn his attack patterns and avoid his tears. Utilize cover when necessary.
• Satan: Stay mobile and avoid his attacks. Focus on dealing damage to his first form before moving on to the second and third forms.
• The Lamb: Avoid his Brimstone attacks and prioritize dealing damage to his head.
• Blue Baby (??): Learn his attack patterns and avoid his tears. Utilize items that provide additional damage.
• Hush: Stay mobile and avoid his attacks. Focus on dealing damage during his vulnerable phases.
• Mega Satan: Learn his attack patterns and avoid his attacks. Utilize powerful items to deal significant damage.
• Delirium: Stay mobile and avoid his attacks. Be prepared for him to transform into other bosses.
• Mother: Learn her attack patterns and avoid her attacks. Utilize items that provide additional damage and defensive capabilities.
• The Beast: Learn her attack patterns and avoid her attacks. Focus on dealing damage to each of her forms in sequence.

Conclusion

Earning all completion marks in The Binding of Isaac is a challenging but rewarding achievement. By understanding the game’s mechanics, utilizing effective strategies, and practicing consistently, you can unlock all the game’s content and demonstrate your mastery. Remember to adapt your strategy to each character and boss, and don’t be afraid to experiment with different item synergies. Good luck, and have fun unlocking all the secrets of The Binding of Isaac. Mastering all completion marks in Isaac requires dedication and practice, but the sense of accomplishment is well worth the effort.