While the act of milling, putting cards from a player's library directly into their graveyard, can be used against an opponent as a win condition, the act of milling one's self can be quite advantageous if a deck is built around it
There are always promotional videos during pro tours, and sometimes you can pick up some interesting tid-bits from them
C Common A Deal with Dark Ruler X SPELL Quick-Play (This card is always treated as an "Archfiend" card.) If a Level 8 or higher monster under your control was sent to the Graveyard this turn: Special Summon 1 "Berserk Dragon" from your hand or Deck
Makes Saturn/Mars OTK that much more dumber (get Saturn/Mars + field out, play this, declare number and proceed to wipe floor)
Upon summoning, it draws you a number of cards equal to the number of Link Monsters your opponents control, plus one, after which you shuffle back one less card than you drew
Por cada mulligan que realice un jugador, su rival puede elegir robar una carta