Establish Undercity

Whenever an opponent discards a creature card
from the bottom of their library create a 1/1
Black rat creature token named Skaven Slave.
Whenever an opponent discards a land card from
the bottom of their library, add {b/g} to your mana
pool at the beginning of your next main phase.
Whenever an opponent discards a non-creature,
non-land, card from the bottom of their library,
gain 1 life.