Build! Breed! Grow!

At the beginning of your upkeep, target opponent
puts the bottom card of their library into their graveyard.
At the beginning of your upkeep, if an opponent
has 10 or more cards in their graveyard,
draw a card.
At the beginning of your upkeep, if an opponent
has 20 or more cards in their graveyard, create
two 1/1 Black rat creature tokens named Skaven
Slave.