In the Hands of the Dice Gods

At the beginning of each player's upkeep, that
player rolls a twenty-sided die. If they roll a 20,
they take an extra turn after this one. If they roll
a 1, they skip their turn.
Whenever a creature attacks, that creature's
controller rolls a twenty-sided die. If they roll a
20, that creature gets +5/+5 and gains vigilance,
flying, trample and menace until end of turn. If
they roll a 1, they sacrifice that creature.