Twice

At the beginning of your end step, create a Twice
Copy token.
Ultimate Move: Infinite Doubles
{x}{t}: Pay X mana, equal to the number of
creatures you control on the battlefield. Create
a Twice Copy token for every Twice Copy token
you control, then copy again. You must pay X
mana, equal to the number of creatures you
control on the battlefield, to untap Twice.