Tarkir, Dragon's Storm

—Once per turn, you may pay {1} plus {x} extra
for every time you have activated this ability (X),
if you do, roll a d20:
• 1: Create X 5/5 dragon token with flying.
• 2-9: Reveal X cards from the {s} pile. Play one without paying.
• 10: Target flying creature gets +X/+X u. t.
{bull} 11-19: Reveal X cards from the {e} pile. Play one without paying.
{bull} 20: You take 3 times X damage.