The Binding of Isaac: Rebirth: Isaac unlocks guide

Trinket; Isaac’s severed head will follow him as a familiar firing piercing tears that deal 3.5 damage with each shot.
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Coop baby; Constantly bleeds small puddles of red creep which can damage enemies.
Releases a larger puddle of creep upon death.
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Active item; Each tear shot by the player increases item charge by one.
Upon use, fires 8 tears around Isaac, which retain the damage, range, shot speed, and most special tear effects of his tears.
(in Repentance) Tears from this item have a +5 flat damage bonus.
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Active item; Reroll all pickups, chests, and trinkets within a room.
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Passive item; Isaac’s tears are replaced by a knife that pierces enemies and can travel through obstacles. Holding down the fire button increases its range and power.

The knife deals damage 20 times per second upon contact with enemies while Isaac is holding it.

The knife deals 2x Isaac’s damage while held and 6x damage at the furthest possible point of its throw distance, regardless of the actual maximum range stat. [b3]Removed in Repentance[/b3]

Damage dealt by the knife depends on its charge state. The knife deals 2x Isaac’s damage when held and 6x damage at about 1/3 of full charge. The knife damage quickly drops to 2x Isaac’s damage when returning regardless of charge state. Further charging only increases its maximum range. [b3]Added in Repentance[/b3]

This item belongs to the (Yes Mother?) set. Collecting three items from this set will transform Isaac into his mother. [b3]Added in Afterbirth[/b3]
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Trinket; (in Rebirth) If Isaac dies to a Sacrifice Room’s spikes, a puzzle piece will appear on his last will.
(except in Rebirth) Dying in a Sacrifice Room while holding the trinket consumes it, revives Isaac as The Lost and unlocks the character.
If The Lost is already unlocked, the trinket works outside Sacrifice Rooms as well, reviving Isaac as The Lost.
(in Repentance) Tainted Lost will remain as Tainted Lost.
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Co-op baby; Occasionally briefly increases Isaac’s tears by 1.
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Passive item; Spawns a familiar that follows Isaac around and blocks enemy projectiles. Upon blocking a shot, it has a 10% chance of farting. There are three possible fart effects:
Charms all nearby enemies.
Poisons all nearby enemies.
Knocks back nearby enemies (in Repentance)and hostile tears.
(in Repentance) This item belongs to the Conjoined set. Collecting three items from this set will transform Isaac into a three-faced version of himself.
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Passive item; Spawns a chest familiar that has a 25% chance to spawn a pickup and a 10% chance to spawn a trinket after clearing a room. The possible rewards are:
Hearts
Coins
Bombs
Keys
Pills
Cards
Runes
Batteries
Trinkets
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Active item; Duplicates 1 random pickup in the current room, including Cards, Runes, Chests, and trinkets.
(in Repentance) Duplicated pickups may not be identical to the original; for example, a duplicated card may be a different one than the original.
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Active item ; (except in Repentance) Grants a random dice item that transforms into a different random dice item upon use.
Each dice item has a 2 room charge.
D infinity is able to use all the available effects, regardless of whether the individual dice mimicked by this item has been unlocked prior or not.
(in Repentance) Acts as any dice item except for Spindown Dice, and can be cycled through by pressing the drop key.
Charge time varies based on the current dice, and updates when used.
D1 has a charge of 4 rooms.
D4 has a charge of 6 rooms.
The D6 has a charge of 6 rooms.
Eternal D6 has a charge of 2 rooms.
D7 has a charge of 3 rooms.
D8 has a charge of 4 rooms.
D10 has a charge of 2 rooms.
D12 has a charge of 3 rooms.
D20 has a charge of 6 rooms.
D100 has a charge of 6 rooms.
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Active item ; Upon use, splits enemies in the room into two smaller versions with ~40% health each.
Normal enemies can be split twice, while champions and bosses can be split three times. If an enemy cannot be split, they instead take 25 damage.
If the enemy splits as part of their mechanic, such as Squirt, Teratoma, or The Fallen, they will instead take the damage required to split them.
If the enemy has segments, such as Larry Jr. or Buttlickers, they will have their segments cut down to half, rounding down. There are several exceptions listed in the notes section.
If the enemy has a cable between them, such as Mr. Maw, it will immediately be cut. Mr. Maws specifically will be left with just their head.
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Passive item ; Upon completing a room, if a room clear reward would spawn, another different reward spawns next to it. If Isaac directly interacts with one, the other disappears.
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Co-op Baby ; Occasionally briefly gives Isaac the Guillotine effect, detaching Isaac’s head and increasing damage and tears.
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