While in a room with enemies, creates a trail of tears that Isaac drags behind him.
Each tear deals 3.5 damage, regardless of Isaac's damage.
The shorter the trail of tears is, the faster it grows.
The trail is composed of 20 tears at max length.
Once the room is cleared, the trail will remain but will stop regenerating.
Another trail of tears may appear if the trail is cut in the middle.
Synergies
Angelic Prism: Splits the trail of tears into four multi-colored chains.
Lachryphagy: Some Akeldama tears will absorb tears shot by Isaac and gain size and damage as expected, but will not burst from being overloaded and can be fed infinite amount of tears. Meaning that each tear, if fed enough, can deal massive amounts of damage.
Lodestone: Magnetized enemies will attract the tears from Akeldama's trail, making it easier to use.
Multidimensional Baby: Akeldama tears that passes through Multidimensional baby will be cloned and may also create a separate trail if enough tears are cloned.
Tear Detonator: Will burst tears generated by Akeldama into Isaac's current tears.
Technology Zero: Shot tears will create a laser between it and the Akeldama tear closest to Isaac.
Dead Eye: The tears in the trail will contribute to the damage boost, making it possible to stack damage while having items that do not interact with Dead Eye on their own (such as Brimstone).
Interactions
Anti-Gravity: Akeldama tears are unaffected by Anti-Gravity.
Akeldama means 'field of blood' in Aramaic, and is thought to be the monastery where Judas Iscariot committed suicide after betraying Christ in the Bible.
The name comes from a passage from the Gospel of Matthew, where after his betrayal, Judas cast his reward of 30 silver pieces into the temple for the priests. The coins were deemed as 'blood money', so instead of adding them to the treasury, a field was bought to bury foreigners (27:7).
An alternative naming origin comes from the Acts of the Apostles, where it is stated that Judas "acquired a field with the reward of his unjust deed, and falling headfirst he burst open in the middle and all his intestines gushed out," (Acts 1:18-19). This telling in particular is likely where the item description comes from.
Angelic Prism: Splits the trail of tears into four multi-colored chains.
Lachryphagy: Some Akeldama tears will absorb tears shot by Isaac and gain size and damage as expected, but will not burst from being overloaded and can be fed infinite amount of tears. Meaning that each tear, if fed enough, can deal massive amounts of damage.
Lodestone: Magnetized enemies will attract the tears from Akeldama's trail, making it easier to use.
Multidimensional Baby: Akeldama tears that passes through Multidimensional baby will be cloned and may also create a separate trail if enough tears are cloned.
Tear Detonator: Will burst tears generated by Akeldama into Isaac's current tears.
Technology Zero: Shot tears will create a laser between it and the Akeldama tear closest to Isaac.
Dead Eye: The tears in the trail will contribute to the damage boost, making it possible to stack damage while having items that do not interact with Dead Eye on their own (such as 
Brimstone).
Anti-Gravity: Akeldama tears are unaffected by Anti-Gravity.
Godhead: Akeldama tears do not have the aura.
Ipecac: Akeldama creates normal tears.
Pop!: Akeldama blocks the eyeballs created by 
Scissors: The trail will follow Isaac's body.
Judas Unlocks 
Mother Unlocks 
The Binding of Isaac: Rebirth
