cumulative upkeep—flip a coin. (at the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

whenever you win a coin flip, karplusan minotaur deals 1 damage to target creature or player.

whenever you lose a coin flip, karplusan minotaur deals 1 damage to target creature or player of an opponent's choice.