Amnesia potion, also known as Amnesia Portion, is a magical chemical in the My Immortal universe. The potion is described as being black colored, peppered with red pentagrams, and typically contained in a cross-shaped bottle. From studying it's effects, we can tell that amnesia potion is essentially a love potion, where causing a person to ingest a certain amount of the mixture will increase feelings of attraction towards another specific individual. However, this is contradictory to the definition of amnesia itself, which is defined as a partial or total loss of memory.
Amnesia potion first sprouts up in Chapter 36. As Enoby drinks some beer mixed with blood during her potions klass, Hairgrid tries to slip some Amnesia potion into her beverage. It is unknown if he had brewed the potion in class, or if he had obtained it from an outside source. After being caught by Darko, he and Vampire beat him up sexily.
This heinous act gives Enoby the idea to utilize Amnesia potion to make Tom Satan Bombadil fall in love with her faster because it's not a crime when heroes do it. She travels back in time in the next chapter to Profesor Slutgorn's efface and pilfers a bottle of it. While at the theater with Satan in Chapter 38, Ebony spikes his branded Nightmare b4 Christmas cigar with the potion. After smoking it, Satan, revealing he was aware of Ebony's plot, explains that the Amnesia potion will not work because it has not been invented yet, even though its mere presence during that time period suggests that, yes, it has been invented. Amnesia potion is never mentioned in the story again after this event.
The name of the potion is possibly based off the canon Harry Potter love potion of Amortentia, the strongest brewable love potion, although the idea of Tara having that much knowledge of the Harry Potter universe is questionable.