+1: Each player discards a card.
−2: Target player sacrifices a creature.
−6: Separate all permanents target player controls into two piles. That player sacrifices all permanents in the pile of their choice.
3/14/2017 When Liliana’s first ability resolves, first the player whose turn it is chooses a card to discard, then each other player in turn order chooses a card to discard, then those cards are discarded simultaneously. No one sees what the other players are discarding before deciding which card to discard.
3/14/2017 The player targeted by Liliana’s second ability chooses which creature to sacrifice when the ability resolves. This ability doesn’t target any creature.
3/14/2017 When Liliana’s third ability resolves, you put each permanent the player controls into one of the two piles. For example, you could put a creature into one pile and an Aura enchanting that creature into the other pile.
3/14/2017 A pile can be empty. If the player chooses an empty pile, no permanents will be sacrificed.