If you don’t have twenty or more creature cards in your graveyard by the time your upkeep starts, the ability won’t trigger that turn.
15-07-2007
wotc
Mortal Combat’s ability has an “intervening ‘if’ clause,” so the condition is checked again when the triggered ability resolves. If you don’t still have twenty creature cards in your graveyard, the ability does nothing.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.