When Oath of Liliana enters the battlefield, each opponent sacrifices a creature.
At the beginning of each end step, if a planeswalker entered the battlefield under your control this turn, create a 2/2 black Zombie creature token.
7/13/2016 Oath of Liliana’s last ability will trigger even if the planeswalker that entered the battlefield under your control is no longer on the battlefield, no longer under your control, or no longer a planeswalker. This is also true if Oath of Liliana wasn’t on the battlefield when the planeswalker entered.
7/13/2016 The last ability triggers only once per turn, even if more than one planeswalker entered the battlefield under your control.
7/13/2016 Oath of Liliana is legendary, just like the previous Oaths from Oath of the Gatewatch. If you already control an Oath of Liliana, you can still cast a second Oath of Liliana to take advantage of its enters-the-battlefield ability. It will enter the battlefield, causing its first ability to trigger. You will then choose one to keep, and the other will be put into your graveyard.