Millstone

, : Target player mills two cards.

Rarity

Set

Number

Rulings

Can be used on a player with less than 2 cards in their library. It will remove 0 or 1 cards if that is all that is available.

It is not a draw effect so it will not cause a player with less than 2 cards in their library to lose.

Since you are putting more than one card in the graveyard at one time, the affected player can choose the order the 2 cards go in.