Shard Of The Cryonix

{t}Double your mana pool.
Roll a D20
1-2: Destroy all creatures you control.
3-4: Deal 7 damage to all creatures you control
5-6: Deal 5 damage to all creatures you control.
7-9: Deal 3 damage to all creatures you control.
10-12: Deal 2 damage to all creatures you control.
13-18: Deal 1 damage to all creatures you control.