If you've mastered fighting Wrath's ability to kick bombs, Dr.Mom's Bra (or Mom's Contacts, though not as reliably) does protect you from collision damage, only with it the bosses won't be running away while you drain two thirds of their lifebar with The Virus. The Book of Shadows gets a special mention because if you have Poison Touch from The Virus to go with it, you've essentially got My Little Unicorn with a faster recharge rate. Mom's Bra or the Book of Shadows can basically win a room by themselves or put the serious hurt on a boss during their duration and can be used once every three rooms.You could theoretically beat some bosses (like Chad) and many other rooms by hovering over a rock and holding down the fire button.
Projectiles and most enemies will not be able to touch you if you're floating over an obstacle, and their projectiles can't penetrate the rocks, but yours will still hit them.
BRIMSTONE TINY PLANET SPOON BENDER PLUS
Flight plus the Ouija board (which lets you shoot through rocks), or the Spirit of the Night item which combines them.All this also gives you a lot more latitude to purchase powerful Devil Room items (which permanently reduce your heart meter). Better yet, it gives you unlimited chances at the Blood Bank, giving you oodles of coins and a very good chance to pick up a Blood Bag, which extends your heart meter.