Just pick up 5 familiars out of the bunch, and go blindfolded! You can't pick up BFFS, Child Leash or Incubus, and you can't reroll your items. Your objective: kill Blue Baby, and Mega Stan if you want.

Familiars are:

???'s Only Friend

Abel

BBF

Bob's Brain

Bomb Bag

Brother Bobby

Bum Friend

Bumbo

Cain's Other Eye

Censer

Charged Baby

Cube of Meat/Ball of Bandages (you can only pick ONE!)

Daddy Longlegs

Dark Bum

Dead Bird

Demon Baby

Dry Baby

Fart Baby

Fate's Reward

Friend Zone

GB Bug

Gemini

Ghost Baby

Guppy's Hairball

Harlequin Baby

Headless Baby

Holy Water

Isaac's Heart

Juicy Sack

Key Bum

Key Pieces, if you want

Leech

Lil' Brimstone

Lil Chest

Lil Gurdy

Lil' Haunt

Lil Loki

Little CHAD

Little Chubby

Little Gish

Little Steven

Lost Fly

Mango Baby

Milk

Multidimensional Baby

Mystery Sack

Obsessed Fan

Papa Fly

Peeper

Punching Bag

Rainbow Baby

Relic

Robo Baby

Robo Baby 2.0

Rotten Baby

Rune Bag

Sack of Pennies

Samson's Chains

Seraphim

Sissy Longlegs

Sister Maggy

Smart Fly

Spidermod

Succubus

Sworn Protector

You can also pick up trinkets that give you familiars like ???'s Soul and Isaac's Head.