Mormir Vig starts on the board and cannot be affected throughout the game in anyway. Players start with a 60 card library which is filed with 12 of each basic land type.

Mormir Vig reads

x, discard a card: Put a token onto the battlefield that is a copy of a creature with the converted mana cost x chosen at random. Activate only this ability only any time you could cast a socery and only once on each of your turns.

This game mode is originally from MTGO, instead of choosing from ALL creatures ever created I'm going to make a cube. So when you activate the ability you chose a pile with corresponding number and cast the top card from that pile.