Kicker and/or
(You may pay the kicker cost in addition to any other costs as you cast this spell.)
As Urborg Lhurgoyf enters the battlefield,
mill (To mill a card, a player puts the top card of their library into their graveyard.) three cards for each time it was kicked.
Urborg Lhurgoyf's power is equal to the number of creature cards in your graveyard and its toughness is equal to that number plus 1.