You’re staring at the shop pedestal in The Binding of Isaac: Repentance. You see that little red crest. It’s the Birthright. You’ve heard people talk about it like it’s the holy grail of items, but there’s a problem. It’s locked. Or maybe you've picked it up and nothing happened. That’s because Birthright is one of the most unique, frustrating, and rewarding unlocks in the entire game. Honestly, if you’re playing the Repentance expansion and you haven't figured out how to unlock birthright isaac yet, you’re playing a significantly harder version of the game.
It changes everything. For Isaac, it lets you see a "ghost" of the item you swap out with the D6. For Tainted Lost, it acts as an extra life—something that character desperately needs. But getting it isn’t just about beating a boss once. It’s about a specific, grueling grind through the game’s most difficult path.
The Jacob and Esau Problem
Let's get the bad news out of the way first. To unlock Birthright, you have to play as Jacob and Esau. I know. Most players hate them. Controlling two characters at once feels like trying to rub your stomach and pat your head while someone throws bricks at you. It’s clumsy. It’s annoying. But they hold the keys to some of the best items in the game, including Damocles and, of course, Birthright.
To get the unlock, you need to defeat Isaac (the boss in the Cathedral) while playing as Jacob and Esau.
That sounds simple on paper. It isn't. You have to manage two hitboxes through bullet-hell patterns that were designed for one. If either of them dies, the run is over. You can’t just buff one and leave the other as a meat shield; you have to balance their health and items perfectly. Most people fail because they let Esau’s health get too low while focusing on Jacob. Don't do that. Treat them like a single, wide entity.
Reaching the Cathedral
Getting to the Cathedral is the "easy" part of the journey. You just need to beat Mom's Heart or It Lives 11 times to permanently unlock the paths to the Polaroid and the Negative. Once you’ve done that, beating Mom’s Heart will spawn a beam of light. Step into that light as the twin brothers.
Once you are in the Cathedral, the real test starts. The rooms are wider, the enemies are faster, and the boss—Isaac himself—has three phases that will absolutely punish you if your characters get separated. If Jacob is in the top left corner and Esau is stuck in the bottom right, you're going to take damage during the "crack the sky" light beam phase. It’s unavoidable. Keep them glued together. Hold that drop button (Ctrl on PC, RT/R2 on console) to lock one in place if you need to micro-adjust their positioning.
Why Birthright is Actually Worth the Headache
So, you went through the pain of playing Jacob and Esau. Why? Because Birthright is arguably the most "meta" item in The Binding of Isaac. It doesn't have a single effect. Its effect changes based on which character you are playing.
For some characters, it's a minor buff. For others, it's a run-winner. Take Tainted Beth. Her Birthright makes it so her temporary wisps don't disappear when she takes damage. That is massive. Or Tainted Jacob—it makes his brother, Dark Esau, split into two. Wait, that actually makes it harder. But that's the beauty of Isaac; it's a game of risk and reward.
- The Lost: Removes some useless items from the item pool (like HP ups).
- Bethany: Allows her to use soul hearts to charge her active item even if she has red hearts.
- Azazel: Gives him a wider, more powerful brimstone beam.
You see the pattern. It’s a custom-tailored power-up. It costs 15 pennies in the shop, which is a steal considering what it does for the endgame characters.
The Secret to Managing the Twins
If you're struggling to get the unlock, here's a tip most "pro" guides skip: focus on the Alternative Path. Go through Downpour and Mines if you can. Why? Because the treasure rooms in the Alt Path have two items—one visible and one hidden behind a question mark. If you position Jacob and Esau correctly, you can walk into both items at the exact same time.
This is the only way to keep their power levels equal. If you go the standard route, you're splitting items between two people, making both of them weak. If you go the Alt Path, you're getting double the loot. It makes the Cathedral run significantly more manageable. Just be careful with the Mines; the traps there are a nightmare for two hitboxes.
What Most People Get Wrong About the Unlock
A common misconception is that you need to beat Blue Baby (the Chest) or The Lamb (the Dark Room) to get Birthright. You don't. You only need to beat Isaac in the Cathedral. I've seen people push all the way to the Chest and die, thinking they failed the unlock, when they actually triggered it the moment the Cathedral boss died.
Check your "Secrets" menu. If you see Secret #619, you're good. It's done. You never have to touch Jacob and Esau again if you don't want to (though you should, because their other unlocks are just as broken).
Another thing: Birthright doesn't show up in every shop. It’s part of the shop pool, but it’s rare. If you have the unlock but never see the item, start donating to your Shop Machine. Leveling up your shop increases the number of items it sells, which naturally increases your odds of seeing that red crest.
Actionable Next Steps
If you’re ready to finally add this item to your pool, follow this exact sequence.
First, spend a few runs just practicing the movement of Jacob and Esau in the early floors. Don't even worry about winning. Just get used to how they move together.
Second, aim for the Cathedral. Ignore the Devil Deals; go for Angel Rooms. Jacob and Esau need the health upgrades that Angel Rooms provide. You cannot afford to trade away heart containers when you have two health bars to maintain.
Third, once you reach the Cathedral, play it slow. Clear every room. You need every bit of soul heart protection you can find before fighting Isaac.
Once the boss falls and the achievement pops, Birthright is officially in your item pool. From that point on, every shop you enter carries the potential to completely break your run wide open. It’s a long road, and Jacob and Esau are frustrating, but the payoff is the single most versatile item in the Repentance expansion. Go get it.