They were made to support the magecraft mechanic, so cards with magecraft and prowess are a good fit
All of these will have their own purpose, and some can be stronger than others depending on what youre looking for, so dont take the self-mill term too literally
Finding an artist with a consistent or unique style opens up designing from the art itself
It has some quality reprints with cards like Ondu Spiritdancer and Hall of Heliod's Generosity, while also being a different take on enchantress
A Moderately Played card may have some form of imperfection impacting a small area of the card from mishandling or poor storage, such as creasing that doesnt affect card integrity, in combination with other issues such as scratches, scuffs or border/edge wear
Once you begin to cast a spell using an emerge ability granted by Herigast, losing control of Herigast won't affect it