Remnant Shard

{t}: Put a Power counter on Remnant
Shard, then add X black mana to your mana
pool, where X is the number of Power counters
on Remnant Shard.
At the end of each turn, roll a d20, then add
the number of Power counters on Remnant
Shard to the roll. If the result is more than 20,
deal X damage to all creatures and lose X life,
where X is the number of power counters on
Remnant Shard. Then, sacrifice Remnant Shard.