Monsters you control gain 300 ATK for each card type (Monster, Spell, or Trap) among your banished cards.
Once per turn, during the Main Phase: You can banish 1 card from your hand or GY, then you can shuffle 1 of your banished cards into the Deck.
If this card is banished; You can place it face-up on your field.
You can only use this effect of "D.D. Post" once per turn.