Milling a card means putting the top card of your library into your graveyard if theres no card to put into the graveyard, no cards were milled
Forbid allows for lock down abuses and can just be a useful discard outlet too
The phenomenon is depicted in an unadorned way in which the actors, without knowing, oddly enough, are directing themselves
Cards are also split into different types: including characters, songs, items, actions and locations
You can't one-for-one remove cards with counterspells and targeted removal, or use a wrath to sweep a few things and expect to be ahead in the current Standard meta
Control and midrange decks appreciate how it thins the deck slightly while guaranteeing future land drops, and Commander players like having a low-opportunity-cost way to fetch whatever basic theyre missing