Mystery Egg#539

“Sacrificial insemination”

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Intro

Mystery Egg is an unlockable passive item added in The Binding of Isaac: Afterbirth † (Booster Pack #5).

Description

[Friendly] Taking damage spawns a friendly enemy
Spawns stronger friends the more rooms are cleared without taking damage

Trivia

Mystery Egg is based on this Steam Workshop item by Strawrat and Aczom.
Enemies who are immediately charmed when you enter the room count towards the unlock. One strategy for unlocking this is to get the Beelzebub transformation early in a run, and then hunt for rooms with multiple higher-tier fly enemies.

Bugs

Bug! When using Extension Cord with Mystery Egg, after the egg turns into a friendly enemy, the electricity shoots out into a random corner of the room. Bug! When the egg turns into a friendly Heart ( Mask + Heart) will sometimes act as the heart companion for a mask already in the room resulting in an unbeatable room.

Data from EID + Fandom (CC BY-SA). Version: Repentance+.