At the start of the horde's third turn, and all subsequent turns the horde takes; Roll a D20, the horde adds rainbow mana equal to the result. The horde then reveals cards from the top of its library until it reveals with total mana value equal to the result without going over. It then casts all creatures cards revealed this way, followed by all noncreature cards revealed this way. If there is any mana left over, it will activate abilities starting with the highest amount.
    If the result of the D20 is twenty, instead you play a random boss card. While a boss is in play, the horde does not lose life.