The special powers possessed by the Alter Egos since birth called id_es. The cheat skill evolved from 『Absorption』. The highest grade of energy drain. It makes draining, copying and scaling down possible.

The process of draining is:

1. The virus produced inside Meltryllis' body is injected into the target in the form of nectar (poison), melting the parameters stolen at that time, such as "experience points", "skills" and "capacity".

2. After that, she absorbs, converts and turns the parameters liquefied by her virus into a part of herself.

Something like that. If it possesses a shape, organic matter, inorganic substance, no matter what it might be, she can drain it, but if it's something shapeless...such things as a spiritual nature or skills, although they can be liquefied, converting them into "something of her own" is difficult so it seems like she can only use them as simple nutrients. Due to this, "experience points" and "capacity" are the main things she can make "her own". In 『CCC』, she managed to pull off a drastic move where she scaled down humans and Servants, shrinking them to minimum size and she sent them into the enemy's body as a virus. In 『FateGO』, making no distinction between friend or foe, it has the effect of reducing (draining) the power of Noble Phantasms while increasing the power of her own.