Eye of the cosmos

{1}Tap all creatures except Eye of the cosmos.
{3}Add 5 mana of any type to your mana pool.
{8}Create an 8/8 dragon token with flying, first strike, menace, and vigilance.
{15} sacrifice this creature and make the opponents loose 50 life.
during your upkeep you gain 2 life and your opponents loose 2 life