Astral Challenge is a room in Heaven's Call, a mod for The Binding of Isaac.

The Astral Challenge Room can spawn in Chapter 2 and 3 with a 10% chance, and in Chapter 5 with a 30% chance. They can appear once per type, per run.

A astral item or a Planetarium item will always spawn in the room. Collecting or absorbing the item will trigger a battle against an astral boss. In the early chapters, this summons an outer planet boss, while in Chapter 5 it summons an inner planet boss.

Attempting to flee the fight will cause the boss to teleport along with Isaac.

While playing as Andromeda, using the active item Gravity Shift inside a regular Challenge Room or Boss Challenge Room transforms it into an Astral Challenge Room. This effect can be activated once per type, per run.

The room has a 50% chance to appear on The Future floor, featuring a unique boss encounter.

The Astral Challenge does not have an associated item pool.

The following special synergies and interactions for Astral Challenge have been documented.

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

• Download Heaven's Call from the Steam Workshop.