Spawns the ghost of a random passive item, which orbits Isaac but can be destroyed. While the ghost is alive, Isaac gains that item's effects.
Quote
"Item summoner"
Effects
Upon use, Lemegeton will grant a random passive item from the current room's item pool.
Multiple of these items may be held at once.
A small ghost of the item will orbit Isaac, similar to the wisps from Book of Virtues.
Upon the ghost taking enough damage from either direct enemy contact or projectiles, the flame will dissipate, causing loss of the corresponding item.
It is possible to have more than one of the same item.
The same passive item can be obtained again after its initial loss.
There is a similar upper limit like Book of Virtues of 26 ghosts: an inner counterclockwise ring of 6, a middle clockwise ring with 8, and an outer counterclockwise ring of 12.
Using Lemegeton while holding 26 ghosts causes the first one to be replaced.