Most decks are designed to win via combat damage, either by whittling down an opponent's life total, or dealing 21 Commander damage. This deck targets a third win condition: If they can't draw a card, they lose.
This deck was built for Mirko Vosk, Mind Drinker to lead it. Other Legendary Creatures in the Dimir colors have been tried, but they are either too costly to cast or just not effective. Szadek, Lord of Secrets is the only other card that truly fits the theme, but his cost is too high for a commander in my personal opinion when Mirko Vosk costs less and presents a similar threat.
This deck is designed to force opponents to take cards from their libraries (draw pile) and place then directly into their graveyards (discard pile). This strategy is known as "milling." The term comes from the card Millstone, which is ironically not included in this deck at the moment.
Nearly every card in this deck is chosen to either mill opponents or benefit from their graveyards. There is one particularly nasty combo option in this deck, too. Mindcrank + Duskmantle Guildmage = infinite combo. Either they run out of cards, or they run out of life.
This is a deck with some fun mechanics that aren't usually seen in a lot of games, but it's definitely more for casual game since it isn't a competitive powerhouse. When it works, it works well. When the cards are against it, it loses. But we can always blame the card gods rather than ourselves when we lose, right? And when I managed to mill out a blue deck that was just dragging the game on for too long, it was glorious.