Liliana's Devotee
Creature — Human Warlock
Zombies you control get +1/+0.
At the beginning of your end step, if a creature died this turn, you may pay 
. If you do, create a 2/2 black Zombie creature token.
Liliana inspires horror in many and fanatical admiration in a few.
Colin Boyer
The List (PLST)
• #M21-109Rulings
If a creature didn't die before your end step begins, the last ability of Liliana's Devotee doesn't trigger at all. The creature may have died before Liliana's Devotee entered the battlefield, however.
(wotc • 2020-06-23)
The triggered ability triggers just once, no matter how many creatures died this turn.
(wotc • 2020-06-23)
While resolving the triggered ability, you can't pay more than {1}{B} to get more than one Zombie token.
(wotc • 2020-06-23)
Rulings
If a creature didn't die before your end step begins, the last ability of Liliana's Devotee doesn't trigger at all. The creature may have died before Liliana's Devotee entered the battlefield, however.
(wotc • 2020-06-23)
The triggered ability triggers just once, no matter how many creatures died this turn.
(wotc • 2020-06-23)
While resolving the triggered ability, you can't pay more than {1}{B} to get more than one Zombie token.
(wotc • 2020-06-23)