Sacrificial Altar is an unlockable active item in The Binding of Isaac, added in the Afterbirth+ DLC.

Sacrifices up to 2 of Isaac's familiars chosen at random, and spawns an item from a preset devil-deal-like list for each of them.

Converts specific familiars:
• Blue Flies, Blue Spiders, Clots, Locusts, Friendly Dips and Minisaacs into Pennies
• Book of Virtues wisps into Half Hearts
• Lemegeton wisps into Half Soul Hearts

Causes a brief Curse of Darkness!.

Cannot sacrifice Incubus when playing as Lilith.

Can sacrifice familiars granted from trinkets, destroying the trinket in the process.

If an angelic familiar is sacrificed ( Guardian Angel / Seraphim / Sworn Protector), 2 Black Hearts will drop as well.

If Isaac already has all items that can be spawned, it will instead spawn 1-2 copies of Pentagram.

This page shows the latest information as of the new Repentance+ (Online Co-op) DLC.
To see information about this item for the previous Repentance version, check this page instead.

Take 50 Deals with the Devil.

Sacrificial Altar can be found in the following item pools:

The following tags are applied to this item:

The following special synergies and interactions for Sacrificial Altar have been documented.

* Note that not all possible synergies and interactions are listed here.

Below is the Internal Item Description as shown in-game.
Note that some stat changes are not displayed here. Please see the main description for the full effects.

Sacrificial Altar

• The altar is consumed to sacrifice up to 2 familiars, chosen at random
• For each familiar sacrificed, 1 random devil room pedestal item is spawned
• Activating it also sacrifices each blue spider or fly, spawning 1 coin each
• Abyss: x1 locust .75x Isaac's damage
• Book of Virtues: x1 middle wisp - 12 hp - 6 damage
• Book of Virtues: All wisps are sacrificed and drop 1/2 each

• Check out the item description on the external Isaac Wiki.