Leviathan

Isaac turns into a Lovecraftian horror, gains 2 black hearts, and gains flight after picking up three of these items.

Activated Collectibles[]

Name	ID	Icon	Quote	Description	Quality
The Nail	5.100.83		Temporary demon form	Gives one Soul Heart half a Black Heart. For the current room; +0.7 damage, -0.18 speed, allows Isaac to break rocks and damage enemies by walking over them.	3
Sulfur	5.100.556		Temporary demon form	Grants Brimstone for the current room.	2

Name	ID	Quote	Description	Quality
Abaddon	5.100.230	Evil + DMG up + fear shot	+1.5 damage, +0.2 speed. Removes all Red Heart containers, grants six Black Hearts, and adds a chance to shoot fear tears. +1.5 damage, +0.2 speed. Grants two Black Hearts, converts all Red Heart containers into Black Hearts, and adds a chance to shoot fear tears.	4
Brimstone	5.100.118	Blood laser barrage	Tears are replaced by a laser beam that pierces through all enemies and obstacles in its path and deals high damage. Can only be fired after a short charge-up period.	4
Pentagram	5.100.51	DMG up	+1 damage, increases Devil Room / Angel Room chance by 10%.	3
Spirit of the Night	5.100.159	Scary	Grants spectral tears and flight.	3
The Mark	5.100.79	DMG + speed up	Grants one Soul Heart, +1 damage, and +0.2 speed.	3
The Pact	5.100.80	DMG + tears up	Grants two Soul Hearts Black Hearts, +0.5 damage, and +0.7 tears.	3
Maw of the Void	5.100.399	Consume thy enemy!	Charged by firing for 2.5 seconds and when released, creates a black ring around Isaac that rapidly deals damage. +1 damage, the ring can cause enemies to drop Black Hearts.	4
Eye of the Occult	5.100.572	DMG up + range up + controlled tears	Isaac's tears are now controlled mid-flight with tear controls. Also increases damage and range, but decreases shot speed.	3

Note: Brimstone no longer counts towards the transformation as of Repentance.

Repentance only:

Name	ID	Icon	Quote	Description	Quality
Lord of the Pit	5.100.82		Demon wings	Grants flight and +0.3 speed.	3

Note: Sanguine Bond has a 1% chance to transform Isaac into Leviathan when he steps on the spikes created by this item.

Concept art for Leviathan along with other transformations that would be implemented into the Afterbirth DLC, by Edmund McMillen. Note that "Sistanis" is an early name of this transformation concept.

This transformation is based on the biblical creature of the same name.
This transformation was initially misspelled as "Levathian" in Afterbirth but has been fixed in Afterbirth+.