Boom! is a passive item.
Sets Bomb count to the maximum of 10.
(: IPECAC • Tough Love • Technology 2 • Mutant Spider • Epic Fetus • Polyphemus • Sacred Heart)
Stat Ups: The Sad Onion • Max's Head • Number One • Blood of the Martyr • Magic Mushroom • Roid Rage • Raw Liver • Lunch • Dinner • Dessert • Breakfast • Rotten Meat • Wooden Spoon • The Belt • Mom's Underwear • Mom's Heels • Mom's Lipstick • Wire Coat Hanger • Steven • Pentagram • The Mark • Growth Hormones • Mini Mushroom • The Pact • Small Rock • Super Bandage • Robo-Baby • Little C.H.A.D. • Little Gish • Little Steve • The Relic • The Halo • Money Equals Power • Blood Bag • Odd Mushroom (Thin) • Odd Mushroom (Large) • Whore Of Babylon • Bucket Of Lard (: Stigmata • Speed Ball • Chemical Peel • Bloody Lust • Cat-O-Nine-Tails • Stem Cells • Tooth Picks • SMB Super Fan! • MEAT! • Magic 8 Ball • Squeezy • Jesus Juice)
Familiars and Orbitals: Brother Bobby • Halo Of Flies • Distant Admiration • Sister Maggy • Guardian Angel • Demon Baby • Dead Bird • Forever Alone • Sack Of Pennies • Bomb Bag (: Bum Friend • The Peeper • Ghost Baby • Harlequin Baby • Daddy Longlegs • Sacrificial Dagger • Rainbow Baby • Holy Water • Guppy's Hair Ball • Abel)
Others: 1UP • The Virus • Less Than Three • Skeleton Key • A Dollar • A Quarter • Boom! • Transcendence • The Compass • PHD • Rosary • XRay Vision • Lucky Foot • Magneto • Treasure Map • The Ladder • Charm Of The Vampire • The Battery • Steam Sale • Dead Cat • Lord Of The Pit • Spelunker Hat • Mr. Mega • The Wafer • 9 Volt • Bobby-Bomb (: Guppy's Tail • Mom's Purse • Bob's Curse • Pageant Boy • Scapular • Infestation • The Mulligan • Habit • Spirit Of The Night • Ankh • Celtic Cross • Mitre • Fate • The Black Bean • Holy Grail • Dead Dove • Pyro • 3 Dollar Bill •Mom's Coin Purse • Box)
(: Guppy's Paw • IV Bag • Best Friend • Remote Detonator • Guppy's Head • Prayer Card • Notched Axe • Crystal Ball • Crack The Sky • The Candle • D20 • Spider Butt • Dad's Key • Portable Slot • White Pony • Blood Rights)
Books: The Bible • The Book of Belial • The Necronomicon • Book Of Revelations • Book of Shadows • Anarchist Cookbook • The Book Of Sin • Monster Manuel (: Telepathy for Dummies)