The Binding of Isaac GuideEditThe Binding of Isaac Tips
Arena - The arena doors only open when you have either full health or at least 6 red hearts and have defeated all the enemies in the room.
It’s usually best to avoid arenas if they just contain an ordinary chest.
Secret – Secret rooms are almost always in between three or more rooms, so if you have extra bombs its worth trying out a square on the map if three rooms surround it. You’ve probably already noticed this too, but the secret room entrance is always located in the middle of the wall.
The secret room of each level is almost always in the space with the most adjacent rooms. For example, if the dungeon features a U shape, the ‘hole’ of the U will have 5 adjacent rooms and will be most likely to be the secret room. Using this tactic eliminates the need for X-Ray Specs or the Spelunker Hat.
Even if you know where the room is by using a Compass, Spelunkey, or the x-ray glasses it is worth mapping out the rest of the dungeon before going into it. If the secret room connects to a shop, treasure room, or arena you will be able to enter them from the secret room without having to fulfill the requirements, sparing you a key or allowing you to enter an arena without full health.
You can also try entering an arena, stealing the treasure, and then exiting through the secret room to avoid having to finish off the enemies that spawn.
Stores vs Treasure Rooms – If you only have one key and a surplus of money (25-30+ coins), I’ve found that it is usually worth going to the store rather than the treasure room if you already have a secondary weapon you really like. The store is usually guaranteed to have a passive upgrade whereas the treasure room is more likely to have a secondary weapon. You may also be able to buy another key if nothing else so it’s usually worth the trip.
Store Sales – If an item in the Store has its price in a red font that means it is on sale. Items on sale are always reduced 50% with the price then rounded up to the nearest penny.
An upgrade called Steam Sale can be found or bought in the store that will permanently make every single item in every single store on sale. Buy this item.
Arcades - Start off by blowing up the skull game because it is pretty much useless unless you really need hearts or keys. Then put as many coins as you’re willing to spend, into the slot machine. If it spit out extra hearts that go over your max, Deposit hearts into the blood machine to try blow it up into blood bag.
Slot Machines – I have to admit I’m always weary of slot machines, but it’s silly to avoid them in the game. If you have a bunch of coins you may as well feed them into the machine, it seems like a 50% chance that you’ll get something. Also, sometimes it gives out huge payouts
You can use items that grant you invincibility including Book of Shadows, The Gamekid, My Little Unicorn, and The Chariot to use blood donation machines multiple times without losing health.
The idea here is to get the maximum amount of spins out of the slot machine because it is really the only one worthwhile if you have a surplus of keys and bombs, which is really you should have if you are wasting money in the arcade. The slot machine will often toss out pills or even better loot on rare occasion, so it is best to spend your money there if you want to really pump up your character.
The Devil Room – Best trades are The Pact, Brimstone, Spirit of the Night, The Mark, Guppy's Head, The Nail and Lucky Foot (better with a D6 charge, so you can pick it up and then reroll it)
How to raise devil room spawn:
No damage on floor = +35% No Red heart damage before boss = +65%
No Red heart damage on boss = +35% A no damage floor will give you a 99% chance at a devil for your first deal.
Blowing up a Beggar (the 3 skull guy in the Arcade counts as well) for an extra 35 %(?) (Doesn't stack after first one on floor.),
Having the Book of Belial gives a 25% Higher Chance of a deal with the devil (When held.) Having The Book of Revelations Gives 35% Higher chance of a deal with the devil (When held.)
Have only one Pentagram: +20% Have multiple Pentagrams: +30% If you took a deal with the devil on the previous floor, the chance of spawn is x0.25
If you took a deal with the devil on the floor before last, the chance of spawn is x0.5 Subsequent deals - floor immediately after deal (x25%) Floors after (x50%). This is of the total so the max you can get after your first is never higher than 67.5%.
Declining a devil deal means you do not get the negative multiplier and also a 50% chance for the room to be an Angel Room. No Angel rooms once you pay for an item in the Devil Room.
Krampus does not count as a devil deal. 10% chance to spawn, 40% chance to spawn once you pay for a devil deal.
Angel Room- Pretty much an extra Treasure Room.
HEAD STRAIGHT TO THE BOSS ROOM.
SAVE YOUR COINS UNTIL AT LEAST YOU HAVE CLEARED OUT EVERY ROOM.
SAME GOES FOR KEYS AND BOMBS.
LEAVE SOUL HEARTS TILL YOU’RE TERRIBLY LOW ON HEALTH, THE BLUE TEMPORARY HEARTS YOU CAN PICK UP ARE BEST LEFT TO FACE THE BOSS…
AFTER DEFEATING A BOSS, SOMETIMES A ROOM OPENS WHERE YOU CAN SELL A BIT OF YOUR SOUL IN EXCHANGE FOR A POWERFUL ITEM. IT’S OFTEN WORTH CONSIDERING (AND EVEN JUST GOING TO TAKE A LOOK, AND SHOOTING THE FIRES OUT WHILST YOU ARE THERE),
How do I get more heart containers?
There are a few ways of getting more heart containers. The first way is to find an upgrade item that increases your max HP. Such items can be found from Item Rooms, Shops, Beggars, or as a drop from a Boss. The second way is to find the pill for that play through that increases your HP. This can be difficult, as there are many pills, and only a couple will give you more heart containers. Finally, if you’re brave, lucky, or have a bit of spare health already, you can donate blood. A blood donation machine has a small chance to drop a blood bag (destroying the machine), which restores 5 HP, and increases your max HP by one. A good tactic is to use it in an Arcade, as both of the other games in that room have a chance to dispense hearts to replace the ones you donate.
Crossing gaps – How do I get across these gaps without a ladder? Bombing a rock adjacent to a gap will blow the rock into the hole, plugging it and making a bridge. However, the bomb must be on the opposite side of the rock. Several items allow you to fly over or cross gaps: Transcendence (collectible), Lord of the Pit(collectible), Ladder (collectible) can cross 1-block gaps, The Bible (charged item), The Pony (charged item, but allows this permanently), Shears (charged item), and The Hanged Man (card). The Magnet (item) will pull items across gaps to you.
How should I prioritize using Items, Keys, and Bombs?
Items that increase your health are very, very important, and you should pick them up whenever you get the chance. Conserve at least one key per level to get into Item Rooms, free items are much better than a few coins or having to buy items. If you have enough coins, and already have an active item you like, try using a key on the shop, because there’s a high chance you’ll be able to buy a key there. Keep bombs for entering Secret rooms, bombing X Rocks and for bombing the various slot machines and blood donation machines, you’ll make much more from those as opposed to bombing chests or single coins.
The darker stones (Blue Rocks marked with a faint X) that sometimes show up can be blown up (with a bomb). This yields items, such as bombs, soul hearts, keys, coins, the ‘small rock’ pickup or reveals a golden chest. § Destroying poo piles and extinguishing fire sometimes yields a coin or a half heart.
Early on, it’s better to save your keys rather than opening up the shop door when you don’t have enough coins to buy anything.
You can use bombs to destroy slot machines, blood donation machines, beggars and the cup game NPC to get items from them. Bombs can be used to open a door in a monster-filled room to escape if you can Totally Handle without Any Significant Issue it (This doesn’t work if the door needs a key) but when you return to the room, all of the enemies will respawn. Bombs can also be used to move items surrounded by spikes away from the danger. This does not work for items surrounded by holes or pits.
If you beat the boss on the current level with full health and there are extra hearts laying around, you can use a blood machine the exact number of times equal to the number of extra half-heart
Having a Ladder/ Transcendence / Lord of the Pit /Horse item can protect you from any melee enemies if you stand over a gap. Keep these items in high priority to get, especially in later floors like The Depths where there are Knights. Bible and Hanged Man can grant flight for one room as well. If you also have the Ouija Board along with a flight item, you can even fly over a rock and shoot enemies while immune to both melee and any non-piercing projectiles.
Pills - Pill effects are randomized each time you play, that is to say that while the orange pill may have given you better tears last game, it may cause you to ♥♥♥♥ bombs the next time you play. While the effects are always random, once you discover a pills effect that pill will have the same effect for the duration of the playthrough.
Secondary Weapons - Secondary weapons recharge by clearing rooms, but not all secondary weapons recharge at the same rate. For instance the Tammy’s Head will recharge every time you clear a room, but the Yum Heart requires six cleared rooms for a full recharge.
You can purchase a Battery from the store that will allow you to recharge items by doing damage, however recharging in this way does not differentiate between items. It will charge each one block at a time no matter what the item is, however this is in addition to the charge you get from clearing rooms so it is almost always a good buy.
Bombing Doors – If you need to escape a room or just don’t want to clear it, regular doors can be forced open by bombing them. This applies to troll bombs and fly bombs as well.
Beggar Kid - If you see one of these you should always try to get at least the first item out of him, if you have a lot of coins you should give him money until he disappears. I’ve gotten everything from tarot cards, to HP upgrades, to secondary weapons out of him before he disappeared. These guys are a ♥♥♥♥ing life line, especially in The Womb, so you should always look out for them.
Soul hearts- buy these right before a boss where it’s critical to have as much health as you can can help get a devil/angel room,
Eternal hearts- grab right before you leave the floor, since if you have one when you move on to the next floor you get a full health container.
Poo and Fire - About ~5% of the time there will be items hidden in poo or fire, you can shoot them to see if they contain anything. It seems to usually be hearts or coins.
Special items in shops can disappear if you leave and then return again.
After you beat the game a sixth time to difficulty increases.