Boss (Item Pool)

Item Pool
Normal/Hard	Treasure Room	Shop	Library	Curse Room	Boss	Secret Room	Devil Room	Angel Room	Golden Chest	Red Chest	Beggar
	Devil Beggar	Key Master	Bomb Bum	Planetarium	Crane Game	Rotten Beggar	Battery Bum	Old Chest	Wooden Chest	Mom's Chest	Baby Shop
Greed Greedier	Treasure Room	Shop	Library	Curse Room	Boss	Secret Room	Devil Room	Angel Room	Golden Chest

The Boss Pool is the pool of items that are dropped by bosses in the Boss Room, barring those with specific set item drops, and can be found in the Boss Challenge Room. This item pool only has passive items. The only other room based item pool that has this property is the Planetarium pool.

Name	ID	Icon	Weight	Description
The Belt	5.100.28		1	Increases speed by 0.3.
Blood Clot	5.100.254		1	Tears fired from the left eye have +1 flat damage, +5 range, and +0.5 tear height.
Blue Cap	5.100.342		1	Gives one full Red Heart container, +0.7 tears, and -0.16 shot speed. Gives one Red Heart container, 2 Hearts of health, +0.7 tears, and -0.16 shot speed.
Box	5.100.198		1	Spawns various pickups: 1 coin, 1 key, 1 bomb, 1 Red Heart, 1 card/rune, 1 pill and 1 trinket.
Breakfast	5.100.25		1	Grants one full Red Heart container. Heals 1 additional heart of health.
Caffeine Pill	5.100.340		1	Grants +0.3 speed, reduces character size, and gives a random pill.
Cat-O-Nine-Tails	5.100.165		1	+1 damage, +0.23 shot speed.
Dessert	5.100.24		1	Grants one full Red Heart container. Heals 1 additional heart of health.
Dinner	5.100.23		1	Grants one full Red Heart container. Heals 1 additional heart of health.
Experimental Treatment	5.100.240		1	Randomly increases and decreases some of Isaac's stats. Increases four random stats and decreases the other two.
Growth Hormones	5.100.70		1	+1 damage, +0.4 speed, +0.2 speed.
Jesus Juice	5.100.197		1	+0.5 damage, +0.25 range, +0.5 tear height.
Latch Key	5.100.343		1	Grants 1 Soul Heart and +1 luck. Spawns 2 Keys.
Little C.H.A.D.	5.100.96		1	Spawns a familiar who drops a Half Red Heart every 3 rooms.
Lunch	5.100.22		1	Grants one full Red Heart container. Heals 1 additional heart of health.
MEAT!	5.100.193		1	Grants one full Red Heart container, +0.3 damage.
Magic 8 Ball	5.100.194		1	+0.16 shot speed, spawns a random tarot card. Increases the chance of finding a Planetarium.
Magic Scab	5.100.253		1	Grants one full Red Heart container, +1 luck.
Match Book	5.100.344		1	Grants Isaac one Black Heart, spawns two or three Bombs.
Mom's Coin Purse	5.100.195		1	Spawns 4 random pills near Isaac.
Mom's Heels	5.100.30		1	+5.25 range, +0.5 tear height. Enemies that touch Isaac take 12 damage.
Mom's Lipstick	5.100.31		1	+5.25 range, +0.5 tear height. Spawns one random heart.
Mom's Underwear	5.100.29		1	+5.25 range, +0.5 tear height. Spawns 3-6 Blue Flies on pickup.
Old Bandage	5.100.219		1	Grants an empty Red Heart container. Adds a chance of dropping a Red Heart after taking damage.
Pageant Boy	5.100.141		1	Spawns seven random coins around Isaac.
Pentagram	5.100.51		1	+1 damage, increases Devil Room / Angel Room chance by 10%.
Placenta	5.100.218		1	Grants one full Red Heart container, and a chance to regenerate a Half Red Heart of health every minute of gameplay.
Roid Rage	5.100.14		1	+0.6 speed, +0.3 speed, +5.25 range, +0.5 tear height.
Rotten Meat	5.100.26		1	Grants one full Red Heart container. Heals 1 additional heart of health.
Safety Pin	5.100.339		1	Grants one Black Heart, +5.25 range, +0.5 tear height, +0.16 shot speed.
Screw	5.100.255		1	+0.5 tears, +0.2 shot speed.
A Snack	5.100.346		1	Grants one full Red Heart container. Heals 1 additional heart of health.
Speed Ball	5.100.143		1	+0.3 speed, +0.2 shot speed.
Squeezy	5.100.196		1	Increases tears by 0.4, spawns 2 Soul Hearts.
Stem Cells	5.100.176		1	Grants one full Red Heart container and +0.16 shot speed.
Synthoil	5.100.345		1	+1 damage, +5.25 range, +0.5 tear height.
Toothpicks	5.100.183		1	+0.7 tears, +0.16 shot speed.
Torn Photo	5.100.341		1	+0.7 tears, +0.16 shot speed.
Wire Coat Hanger	5.100.32		1	Increases tears by 0.7.
Wooden Spoon	5.100.27		1	Increases speed by 0.3.
Super Bandage	5.100.92		1 0.5	Grants one full Red Heart container and 2 Soul Hearts.
<3	5.100.15		1	Grants Isaac one Red Heart container and fully restores Isaac's health.
The Halo	5.100.101		1	Grants one full Red Heart container, +0.3 damage, +0.2 tears, +0.25 range, +0.3 speed, and +0.5 tear height.
Little Steven	5.100.100		1	Spawns a familiar who follows Isaac around and fires homing tears.
Magic Mushroom	5.100.12		1	Makes Isaac bigger. Adds one Red Heart container, +0.3 damage, x1.5 damage multiplier, +5.25 range, and +0.3 speed. Restores all health on pickup.
Binky	5.100.438		1	Grants one Soul Heart, +0.75 tears and decreases Isaac's size.
Crack Jacks	5.100.354		1	Grants one full Red Heart container and drops a random trinket.
Mom's Pearls	5.100.355		1	+1.25 range, +0.5 tear height, +1 luck. Grants one Soul Heart.
Mr. Dolly	5.100.370		1	+0.7 tears, +5.25 range, +0.5 tear height, spawns 3 random types of Hearts on the floor when picked up.
PJs	5.100.428		1 0.5	Grants 4 Soul Hearts and fully restores Isaac's health.
Dad's Lost Coin	5.100.455		1	+1.5 range. Drops a Lucky Penny.
Divorce Papers	5.100.547		1	Grants one Bone Heart, +0.7 tears, spawns a Mysterious Paper.
Marbles	5.100.538		1	Spawns 3 random trinkets, 5% chance to swallow held trinket after taking damage, gaining its effect permanently.
Marrow	5.100.541		1	Grants one bone heart and spawns three red heart pickups.
Midnight Snack	5.100.456		1	Grants one full Red Heart container. Heals 1 additional heart of health.
Belly Button	5.100.458		1	Drops a random trinket. Grants a second trinket slot.
Polydactyly	5.100.454		1	Allows Isaac to carry two cards, pills, or any combination of both. Spawns one random card, rune, or pill.
A Bar of Soap	5.100.564		1	Gives Isaac +0.5 Tears and +0.2 Shot Speed.
Booster Pack	5.100.624		1	Spawns 5 random cards.
Consolation Prize	5.100.644		1	Increases Isaac's lowest stat and drops either 3 coins, 1 bomb, or 1 key depending on what Isaac has the least of.
Eye Drops	5.100.600		1	Lowers the tear delay in Isaac's left eye, causing his eyes to fire at different rates.
Stapler	5.100.708		1	+1 damage. Prevents Isaac from firing tears from one eye, like Cain.
Supper	5.100.707		1	Grants one full Red Heart container. Heals 1 additional heart of health.
Tropicamide	5.100.659		1	+1.5 range, Increases tear size.

Trivia

• Most items in this pool will increase stats, increase health, grant pickups, grant trinkets, or some combination of the four. The ones that don't, Little Steven, Little C.H.A.D., and Little Gish, are familiars that will always drop from the boss they are themed after, respectively Steven, C.H.A.D., and Gish. Said bosses are all references to previous games made by Edmund McMillen, and all of them need to be unlocked by beating the chapter they appear in a certain amount of times.