Virelian, Sky weaver

at the beginning of each upkeep sacrifice all creatures without flying then put a 1/1 on creatures you control for each creature you sacrificed this way.
{3}: Put a 1/1 colorless worm creature with flying onto the battle field.
{t}: tap X creatures where X is the number of creatures with flying you control.
{t}{10}: Gain control of every creature with flying. gain control of every creature with trample.