On use, emits a stream of blue flames in whichever direction Isaac is facing. Each flame deals 1.5 - 2.1 damage per tick, depending on how far it's traveled, for 22.5-31.5 damage per second. Multiple flames can damage the same enemy simultaneously.
Isaac is also pushed backwards slightly while using it.
Can be fired diagonally, or in any direction if using a gamepad.
With each floor damage increases by 0.3 damage per tick.
The fire destroys enemy projectiles, poop, and other fires, but bounces off rocks.
Killing enemies grants a soul charge to the Urn, up to a maximum of 20. Killing bosses grants a larger boost. Charges must be used to power Urn of Souls.
Each charge is equivalent to 15 flames over half a second.
Dogma does not provide any souls when transitioning from its first phase to its second.
On PC, it is possible to control Urn of Souls with the mouse for precise aiming. On Windows, go to C:/Users/[username]/Documents/My Games/The Binding Of Isaac [Rebirth/Afterbirth/Afterbirth+/Repentance]/ and in the options.ini file, change the line that says MouseControl=0 to MouseControl=1. It is also possible to do this with a gamepad with no modifications needed.
Angelic Prism: Flames can be split into four multi-colored flames.
Bird's Eye / Ghost Pepper: The urn can emit flames from these items. Ghost Pepper flames are indistinguishable from Urn of Souls flames, but persist on the ground for longer.
Lead Pencil: Every 15 flames shot out of the urn will shoot a barrage of Isaac's tears.
Multidimensional Baby: All flames shot through Multidimensional Baby are doubled, providing a burst of flashing black-and-white tears.
Book of Virtues: A wisp spawns for every consecutive second Urn of Souls is fired. The occasional fires shot by the wisps block enemy shots, deal contact damage to enemies, and last for 3 seconds before dissipating. The flames deal 10 damage per tick for the first second they're out, scale down to 5 damage over the next second, and then stay at 5 damage until they dissipate (60-30 damage per second). The damage these fires deal does not increase with BFFS! or scale up on later floors.